Write documentation for each CI workflow

.github/workflows/clippy_dev.yml

@@ -1,3 +1,5 @@
+# This action runs tests specific to `clippy_dev`, accessing through the `cargo dev` command. It
+# both checks the project as a whole and tests `clippy_dev`'s commands specifically.
 name: Clippy Dev Test
 
 on:

.github/workflows/clippy_mq.yml

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+# This action runs Clippy's test suite, as well as a few larger and more in-depth tests to verify
+# that the pull request is ready to be merged. (This action is run as part of the [merge queue].)
+#
+# [merge queue]: https://github.com/rust-lang/rust-clippy/queue/
 name: Clippy Test (merge queue)
 
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.github/workflows/clippy_pr.yml

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+# This action runs Clippy's test suite for all of its crates.
 name: Clippy Test
 
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.github/workflows/deploy.yml

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+# This actions generates the documentation available at <https://rust-lang.github.io/rust-clippy>
+# using [`deploy.sh`] and [Github Pages].
+#
+# [`deploy.sh`]: ../deploy.sh
+# [Github Pages]: https://pages.github.com
 name: Deploy
 
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.github/workflows/lintcheck.yml

@@ -1,3 +1,9 @@
+# This action runs [Lintcheck] on on the current pull request and its target branch (which is
+# usually `master`), and compares the results. If they are different, a [job summary] is created
+# with the changes.
+#
+# [Lintcheck]: ../../lintcheck
+# [job summary]: https://docs.github.com/en/actions/writing-workflows/choosing-what-your-workflow-does/workflow-commands-for-github-actions#adding-a-job-summary
 name: Lintcheck
 
 on: pull_request

.github/workflows/remark.yml

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+# This action uses [Remark] to lint all the Markdown files in this repository. It also runs
+# [Linkchecker], which is used to validate links within the Clippy Book. (Not to be confused with
+# Lintcheck, which checks lints!)
+#
+# [Remark]: https://www.npmjs.com/package/remark
+# [Linkchecker]: https://github.com/rust-lang/rust/tree/master/src/tools/linkchecker
 name: Remark
 
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