Add hasura API schema. (#14)

* Add hasura API schema.

Author: dzmitryhil

README.md

@@ -73,3 +73,19 @@ This is expected since the node doesn't store all staking pool for all heights.
 In case you want to integrate the indexing if the custom types, for example parameters,
 that [PR](https://github.com/CoreumFoundation/bdjuno/pull/4)
 can be taken as a reference implementation.
+
+## Hasura API
+
+### GraphQL Schema
+
+The GraphQL schema is located [here](./hasura/api/schema.graphql). It describes all supported queries.
+
+In order to export it you can run the hasura locally and execute script
+
+```
+npm install -g graphqurl # install the gq
+gq http://localhost:8080/v1/graphql -H "X-Hasura-Admin-Secret: myadminsecretkey" --introspect > schema.graphql  # export schema
+```
+
+Pay attention that `myadminsecretkey` is the secret set for this repo local environment, and can be different for
+others.

hasura/api/.graphqlconfig

@@ -0,0 +1,15 @@
+{
+  "name": "Explorer Schema",
+  "schemaPath": "schema.graphql",
+  "extensions": {
+    "endpoints": {
+      "Remote SWAPI GraphQL Endpoint": {
+        "url": "http://localhost:8080/v1/graphql",
+        "headers": {
+          "user-agent": "JS GraphQL"
+        },
+        "introspect": true
+      }
+    }
+  }
+}