[docs] Relocate "appendix" content (#18260)

Move content that was previously structured in the generic "appendix"
directory according to the use case it describes.

Author: jugglinmike

docs/appendix/index.md

@@ -53,10 +53,9 @@ free to add yourself to the META.yml file!
    writing-tests/index
    reviewing-tests/index
    admin/index
-   appendix/index
 ```
 
 [public-test-infra]: https://lists.w3.org/Archives/Public/public-test-infra/
 [IRC]: irc://irc.w3.org:6667/testing
 [web irc]: http://irc.w3.org
-[github-intro]: appendix/github-intro
+[github-intro]: writing-tests/github-intro

docs/index.md

@@ -76,8 +76,8 @@ If you do not expect work with more PRs from the same author,
 you may also discard your connection to their repo:
 `git remote remove <author-id>`
 
-[clone]: ../appendix/github-intro.html#clone
-[commit]: ../appendix/github-intro.html#commit
-[configure]: ../appendix/github-intro.html#configure-remote-upstream
-[fork]: ../appendix/github-intro.html#fork-the-test-repository
-[submit]: ../appendix/github-intro.html#submit
+[clone]: ../writing-tests/github-intro.html#clone
+[commit]: ../writing-tests/github-intro.html#commit
+[configure]: ../writing-tests/github-intro.html#configure-remote-upstream
+[fork]: ../writing-tests/github-intro.html#fork-the-test-repository
+[submit]: ../writing-tests/github-intro.html#submit

docs/reviewing-tests/git.md

@@ -10,6 +10,7 @@ suites, test contributions must be reviewed by a peer.
    checklist
    email
    git
+   reverting
 ```
 
 ## Test Review Policy

docs/reviewing-tests/index.md

@@ -29,6 +29,8 @@ There's also a load of [general guidelines](general-guidelines) that apply to al
    tools
    visual
    wdspec
+   test-templates
+   github-intro
 ```
 
 ## Test Type

docs/appendix/reverting.md renamed to docs/reviewing-tests/reverting.md

@@ -31,7 +31,7 @@ on, e.g. `git checkout -b topic-name`
   request will be automatically merged.
 
 For detailed guidelines on setup and each of these steps, please refer to the
-[Github Test Submission](../appendix/github-intro) documentation.
+[Github Test Submission](../writing-tests/github-intro) documentation.
 
 Hop on to the [mailing list][public-test-infra] or [IRC][]
 ([webclient][web irc], join channel `#testing`) if you have an issue.  There is