https://github.com/civicrm/civicrm-dev-docs/pull/425#issuecomment-338253390

Page should not link to itself.

I'd like to be able to merge the general, incremental improvements for the
"Testing" section, but these two new pages aren't yet written.  Comment them
out.

 * Provide a better visualization of the the different test suites
 * Migrate setup instructions from https://github.com/civicrm/civicrm-core/blob/master/tests/README.md

There are multiple tools for testing in JS. We'll want separate pages for each.

The second statement doesn't make much sense without the first statement.
Put them together.

Running civilint is important for any/all code.  Seems a bit arbitrary
emphasizing this point specifically for tests.

related:
https://github.com/civicrm/civicrm-user-guide/pull/232

Resolve #316

If a reader has customized their interactive shell, their system could have
small discrepancies in shell notation.  It shouldn't matter 95% of the time,
and it's not critical to support those folks perfectly.  But it is nice.  So
let's just share the link to heighten awareness.

(Example: I usually do `export VAR=value`...  but in future docs, I'll try
to use `VAR=value; export VAR`.)

This is following-up on some comments from @ginkgomzd who found the
`bash-hackers.org` site and shared it on https://github.com/civicrm/civicrm-buildkit/pull/365

 * Simplify titles under "Common standards". (Use a noun-phrase instead of an imperative statement.)
 * Combine `r-ext`, `r-core` into r-technical. Add more details. Reference `#gotchas`.
 * Rename `r-read` to `r-code`
 * Rename `rg-schema` to `rg-upgrade`. Add more details.