add README, other minor changes

- API file is now in README
- bump year in LICENSE
- go mod tidy

Author: twmb

API

@@ -1,4 +1,4 @@
-Copyright 2019, Travis Bischel.
+Copyright 2020, Travis Bischel.
 All rights reserved.
 
 Redistribution and use in source and binary forms, with or without

LICENSE

@@ -0,0 +1,121 @@
+kcl
+===
+
+kcl is a complete, pure Go command line Kafka client. Think of it as your
+one stop shop to do anything you want to do with Kafka. Producing, consuming,
+transacting, administrating, and so on.
+
+Unlike the small size of [kafkacat][1], this binary is ~12M compiled.
+It is, however, still fast, has rich consuming and producing formatting
+options, and a complete Kafka administration interface.
+
+[1]: https://github.com/edenhill/kafkacat
+
+## Configuration
+
+kcl supports configuration through a config file, environment variables, and
+config flag overrides, with the config values being defined in that order.
+By default, kcl searches your OS's user config dir for a `kcl` directory and
+a `config.toml` file in that directory. The default path can be overridden.
+As well, multiple configs can easily swapped between with `kcl myconfig`.
+
+The configuration supports TLS, SASL (currently PLAIN and SCRAM), seed brokers,
+and a timeout for requests that take timeouts.
+
+## Autocompletion
+
+Thanks to [cobra][2], autocompletion exists for bash, zsh, and powershell.
+
+[2]: https://github.com/spf13/cobra
+
+As an example of what to put in your .bashrc,
+
+```bash
+if [ -f /etc/bash_completion ] && ! shopt -oq posix; then
+    . /etc/bash_completion
+    . <(kcl misc gen-autocomplete -kbash)
+fi
+```
+
+## Transactions
+
+Transactions are supported by consuming a batch of records, executing a command
+and passing the records to the command's STDIN, reading the modified records
+via the command's STDOUT, and publishing those records.
+
+Input to the program and output from the program is controlled through the same
+syntax as consuming and producing, and the `--rw` flag is a shortcut to say that
+the input and output will use the same format.
+
+As an example, the following command:
+
+```
+kcl transact -rw '%V{b4}%v' -dtxn -g group -t foo -x mytxn -v ./command
+```
+
+reads topic `foo` in group `group`, executes `./command`, writes all record
+values to it prefixed with the four byte big endian value length, reads
+back records in the same format, and produces to topic `txn` all using the
+transactional id `mytxn`.
+
+## Group Consuming
+
+Group consuming is supported with the `-g` or `--group` flag to `kcl consume`
+or `kcl transact`. The default balancer is the cooperative-sticky balancer,
+which was introduced with incremental rebalancing in Kafka 2.4.0. This balancer
+is incompatible with the previous eager balancers (roundrobin, range, sticky),
+thus if you are using kcl with existing groups that have members using eager
+balancing strategies, be sure to specify a different balancer.
+
+## API at a glance
+
+Be sure to `--help` any command before using it to understand the full syntax.
+
+```
+kcl
+ consume
+ produce
+ transact
+ misc
+   api-versions
+   probe-version
+   gen-autocomplete
+   errcode
+   raw-req
+   list-offsets
+ admin
+   elect-leaders
+   delete-records
+   alter-partition-assignments
+   list-partition-reassignments
+   alter-replica-log-dirs
+   describe-log-dirs
+ dtoken
+   create
+   renew
+   describe
+   expire
+ acl
+   create
+   describe
+   delete
+ group
+   list
+   describe
+   delete
+   offset-delete
+ topic
+   create
+   delete
+   add-partitions
+ metadata
+ configs
+   alter
+   describe
+ myconfig
+   unlink
+   link
+   dump
+   help
+   ls
+```

README.md

@@ -19,6 +19,7 @@ github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSs
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/dgrijalva/jwt-go v3.2.0+incompatible/go.mod h1:E3ru+11k8xSBh+hMPgOLZmtrrCbhqsmaPHjLKYnJCaQ=
 github.com/dgryski/go-sip13 v0.0.0-20181026042036-e10d5fee7954/go.mod h1:vAd38F8PWV+bWy6jNmig1y/TA+kYO4g3RSRF0IAv0no=
+github.com/frankban/quicktest v1.7.2 h1:2QxQoC1TS09S7fhCPsrvqYdvP1H5M1P1ih5ABm3BTYk=
 github.com/frankban/quicktest v1.7.2/go.mod h1:jaStnuzAqU1AJdCO0l53JDCJrVDKcS03DbaAcR7Ks/o=
 github.com/fsnotify/fsnotify v1.4.7/go.mod h1:jwhsz4b93w/PPRr/qN1Yymfu8t87LnFCMoQvtojpjFo=
 github.com/ghodss/yaml v1.0.0/go.mod h1:4dBDuWmgqj2HViK6kFavaiC9ZROes6MMH2rRYeMEF04=
@@ -37,6 +38,7 @@ github.com/golang/snappy v0.0.1 h1:Qgr9rKW7uDUkrbSmQeiDsGa8SjGyCOGtuasMWwvp2P4=
 github.com/golang/snappy v0.0.1/go.mod h1:/XxbfmMg8lxefKM7IXC3fBNl/7bRcc72aCRzEWrmP2Q=
 github.com/google/btree v1.0.0/go.mod h1:lNA+9X1NB3Zf8V7Ke586lFgjr2dZNuvo3lPJSGZ5JPQ=
 github.com/google/go-cmp v0.2.0/go.mod h1:oXzfMopK8JAjlY9xF4vHSVASa0yLyX7SntLO5aqRK0M=
+github.com/google/go-cmp v0.3.1 h1:Xye71clBPdm5HgqGwUkwhbynsUJZhDbS20FvLhQ2izg=
 github.com/google/go-cmp v0.3.1/go.mod h1:8QqcDgzrUqlUb/G2PQTWiueGozuR1884gddMywk6iLU=
 github.com/gorilla/securecookie v1.1.1/go.mod h1:ra0sb63/xPlUeL+yeDciTfxMRAA+MP+HVt/4epWDjd4=
 github.com/gorilla/sessions v1.2.0/go.mod h1:dk2InVEVJ0sfLlnXv9EAgkf6ecYs/i80K/zI+bUmuGM=
@@ -46,6 +48,7 @@ github.com/grpc-ecosystem/go-grpc-prometheus v1.2.0/go.mod h1:8NvIoxWQoOIhqOTXgf
 github.com/grpc-ecosystem/grpc-gateway v1.9.0/go.mod h1:vNeuVxBJEsws4ogUvrchl83t/GYV9WGTSLVdBhOQFDY=
 github.com/hashicorp/go-uuid v1.0.2/go.mod h1:6SBZvOh/SIDV7/2o3Jml5SYk/TvGqwFJ/bN7x4byOro=
 github.com/hashicorp/hcl v1.0.0/go.mod h1:E5yfLk+7swimpb2L/Alb/PJmXilQ/rhwaUYs4T20WEQ=
+github.com/inconshreveable/mousetrap v1.0.0 h1:Z8tu5sraLXCXIcARxBp/8cbvlwVa7Z1NHg9XEKhtSvM=
 github.com/inconshreveable/mousetrap v1.0.0/go.mod h1:PxqpIevigyE2G7u3NXJIT2ANytuPF1OarO4DADm73n8=
 github.com/jcmturner/aescts/v2 v2.0.0/go.mod h1:AiaICIRyfYg35RUkr8yESTqvSy7csK90qZ5xfvvsoNs=
 github.com/jcmturner/dnsutils/v2 v2.0.0/go.mod h1:b0TnjGOvI/n42bZa+hmXL+kFJZsFT7G4t3HTlQ184QM=
@@ -61,8 +64,10 @@ github.com/klauspost/compress v1.10.10 h1:a/y8CglcM7gLGYmlbP/stPE5sR3hbhFRUjCBfd
 github.com/klauspost/compress v1.10.10/go.mod h1:aoV0uJVorq1K+umq18yTdKaF57EivdYsUV+/s2qKfXs=
 github.com/konsorten/go-windows-terminal-sequences v1.0.1/go.mod h1:T0+1ngSBFLxvqU3pZ+m/2kptfBszLMUkC4ZK/EgS/cQ=
 github.com/kr/logfmt v0.0.0-20140226030751-b84e30acd515/go.mod h1:+0opPa2QZZtGFBFZlji/RkVcI2GknAs/DXo4wKdlNEc=
+github.com/kr/pretty v0.1.0 h1:L/CwN0zerZDmRFUapSPitk6f+Q3+0za1rQkzVuMiMFI=
 github.com/kr/pretty v0.1.0/go.mod h1:dAy3ld7l9f0ibDNOQOHHMYYIIbhfbHSm3C4ZsoJORNo=
 github.com/kr/pty v1.1.1/go.mod h1:pFQYn66WHrOpPYNljwOMqo10TkYh1fy3cYio2l3bCsQ=
+github.com/kr/text v0.1.0 h1:45sCR5RtlFHMR4UwH9sdQ5TC8v0qDQCHnXt+kaKSTVE=
 github.com/kr/text v0.1.0/go.mod h1:4Jbv+DJW3UT/LiOwJeYQe1efqtUx/iVham/4vfdArNI=
 github.com/magiconair/properties v1.8.0/go.mod h1:PppfXfuXeibc/6YijjN8zIbojt8czPbwD3XqdrwzmxQ=
 github.com/matttproud/golang_protobuf_extensions v1.0.1/go.mod h1:D8He9yQNgCq6Z5Ld7szi9bcBfOoFv/3dc6xSMkL2PC0=
@@ -108,8 +113,8 @@ github.com/twmb/go-rbtree v1.0.0 h1:KxN7dXJ8XaZ4cvmHV1qqXTshxX3EBvX/toG5+UR49Mg=
 github.com/twmb/go-rbtree v1.0.0/go.mod h1:UlIAI8gu3KRPkXSobZnmJfVwCJgEhD/liWzT5ppzIyc=
 github.com/twmb/go-strftime v0.0.0-20190915101236-e74f7c4fe4fa h1:eq9HJTMjHC3K/GYE7RuvhweBhIxXi9y6BYM6Aox3UbA=
 github.com/twmb/go-strftime v0.0.0-20190915101236-e74f7c4fe4fa/go.mod h1:k1GNMjGU8BvbV6Ej1ysLoM1cPfmybe216l51R7RKIf0=
-github.com/twmb/kafka-go v0.4.0 h1:jI2+cdwOAJ3zJB1RFhMZ2LWGXEy4B9SapBDU0G2HtYs=
-github.com/twmb/kafka-go v0.4.0/go.mod h1:wWLRH8FOgeah2itKZJnOjZovXE3GbfWTLIcgR/09GKs=
+github.com/twmb/kafka-go v0.4.1 h1:AL7GKnYXofXCMW4H73xRUQzZFIg63mKEcFaCO6Hox0s=
+github.com/twmb/kafka-go v0.4.1/go.mod h1:wWLRH8FOgeah2itKZJnOjZovXE3GbfWTLIcgR/09GKs=
 github.com/ugorji/go v1.1.4/go.mod h1:uQMGLiO92mf5W77hV/PUCpI3pbzQx3CRekS0kk+RGrc=
 github.com/xiang90/probing v0.0.0-20190116061207-43a291ad63a2/go.mod h1:UETIi67q53MR2AWcXfiuqkDkRtnGDLqkBTpCHuJHxtU=
 github.com/xordataexchange/crypt v0.0.3-0.20170626215501-b2862e3d0a77/go.mod h1:aYKd//L2LvnjZzWKhF00oedf4jCCReLcmhLdhm1A27Q=