rename "common-mistake" label to "faq"

- update & sort exempt labels in stalebot config
- update `MAINTAINERS.md`
- lint markdown

Signed-off-by: Christopher Hiller <boneskull@boneskull.com>

.github/ISSUE_TEMPLATE.md

@@ -9,7 +9,7 @@ For more, check out the Mocha Gitter chat room: https://gitter.im/mochajs/mocha
 Place an `x` between the square brackets on the lines below for every satisfied prerequisite.
 -->
 
-- [ ] Checked that your issue isn't already filed by cross referencing [issues with the `common mistake` label](https://github.com/mochajs/mocha/issues?utf8=%E2%9C%93&q=is%3Aissue%20label%3Acommon-mistake%20)
+- [ ] Checked that your issue hasn't already been filed by cross-referencing [issues with the `faq` label](https://github.com/mochajs/mocha/issues?utf8=%E2%9C%93&q=is%3Aissue%20label%3Afaq%20)
 - [ ] Checked next-gen ES issues and syntax problems by using the same environment and/or transpiler configuration without Mocha to ensure it isn't just a feature that actually isn't supported in the environment in question or a bug in your code.
 - [ ] 'Smoke tested' the code to be tested by running it outside the real test suite to get a better sense of whether the problem is in the code under test, your usage of Mocha, or Mocha itself
 - [ ] Ensured that there is no discrepancy between the locally and globally installed versions of Mocha. You can find them with: `node node_modules/.bin/mocha --version`(Local) and `mocha --version`(Global). We recommend avoiding the use of globally installed Mocha.

.github/stale.yml

@@ -4,28 +4,25 @@ daysUntilStale: 120
 daysUntilClose: 14
 # Issues with these labels will never be considered stale
 exemptLabels:
-  - help-wanted
-  - confirmed-bug
-  - future
-  - chore
-  - feature
-  - unconfirmed-bug
-  - usability
   - browser
-  - reporter
-  - feature
+  - chore
+  - confirmed-bug
+  - developer-experience
   - documentation
-  - nice-to-have
+  - faq
+  - feature
+  - future
+  - good-first-issue
+  - help-wanted
   - needs-review
+  - nice-to-have
   - qa
-  - usability
-  - semver-minor
+  - reporter
   - semver-major
+  - semver-minor
   - semver-patch
-  - reporter
-  - common-mistake
-  - developer-experience
-  - good-first-issue
+  - unconfirmed-bug
+  - usability
 # Label to use when marking an issue as stale
 staleLabel: stale
 # Comment to post when marking an issue as stale. Set to `false` to disable

MAINTAINERS.md

@@ -157,7 +157,7 @@ Support questions should be answered if possible, but the user should be directe
 
 If it's *not* a Mocha problem (people tend not to believe this), you may want to show a counter-example.  It's often helpful to direct the issue author to the responsible project, if you can determine what that is.
 
-- `common-mistake`: Issues which are *repeatedly* asked support questions or misunderstandings.  This may also apply to questions which receive a lot of 👍's
+- `faq`: Issues which are *repeatedly* asked support questions or misunderstandings.  This may also apply to questions which receive a lot of 👍's
 - `question`: Add this label if it's just a support question
 
 ### Bugs

docs/index.md

@@ -1163,7 +1163,7 @@ The "markdown" reporter generates a markdown TOC and body for your test suite. T
 
 ### XUnit
 
-The `xunit` reporter is also available.  It outputs an XUnit-compatible XML document, often applicable in CI servers. 
+The `xunit` reporter is also available.  It outputs an XUnit-compatible XML document, often applicable in CI servers.
 
 By default, it will output to the console.  To write directly to a file, use `--reporter-options output=filename.xml`.