Update check-spelling to v0.0.21

.github/actions/spelling-data/README.md

@@ -8,6 +8,7 @@ File | Purpose | Format | Info
 [excludes.txt](excludes.txt) | Files to ignore entirely | perl regular expression | [excludes](https://github.com/check-spelling/check-spelling/wiki/Configuration-Examples%3A-excludes)
 [only.txt](only.txt) | Only check matching files (applied after excludes) | perl regular expression | [only](https://github.com/check-spelling/check-spelling/wiki/Configuration-Examples%3A-only)
 [patterns.txt](patterns.txt) | Patterns to ignore from checked lines | perl regular expression (order matters, first match wins) | [patterns](https://github.com/check-spelling/check-spelling/wiki/Configuration-Examples%3A-patterns)
+[candidate.patterns](candidate.patterns) | Patterns that might be worth adding to [patterns.txt](patterns.txt) | perl regular expression with optional comment block introductions (all matches will be suggested) | [candidates](https://github.com/check-spelling/check-spelling/wiki/Feature:-Suggest-patterns)
 [line_forbidden.patterns](line_forbidden.patterns) | Patterns to flag in checked lines | perl regular expression (order matters, first match wins) | [patterns](https://github.com/check-spelling/check-spelling/wiki/Configuration-Examples%3A-patterns)
 [expect.txt](expect.txt) | Expected words that aren't in the dictionary | one word per line (sorted, alphabetically) | [expect](https://github.com/check-spelling/check-spelling/wiki/Configuration#expect)
 [advice.md](advice.md) | Supplement for GitHub comment when unrecognized words are found | GitHub Markdown | [advice](https://github.com/check-spelling/check-spelling/wiki/Configuration-Examples%3A-advice)

.github/actions/spelling-data/advice.md

@@ -1,5 +1,5 @@
 <!-- See https://github.com/check-spelling/check-spelling/wiki/Configuration-Examples%3A-advice --> <!-- markdownlint-disable MD033 MD041 -->
-<details><summary>If the flagged items are false positives</summary>
+<details><summary>If the flagged items are :exploding_head: false positives</summary>
 
 If items relate to a ...
 * binary file (or some other file you wouldn't want to check at all).
@@ -14,7 +14,9 @@ https://www.regexplanet.com/advanced/perl/) yours before committing to verify it
 
 * well-formed pattern.
 
-  If you can write a [pattern](https://github.com/check-spelling/check-spelling/wiki/Configuration-Examples:-patterns) that would match it,
+  If you can write a [pattern](
+https://github.com/check-spelling/check-spelling/wiki/Configuration-Examples:-patterns
+) that would match it,
   try adding it to the `patterns.txt` file.
 
   Patterns are Perl 5 Regular Expressions - you can [test](
@@ -23,3 +25,7 @@ https://www.regexplanet.com/advanced/perl/) yours before committing to verify it
   Note that patterns can't match multiline strings.
 
 </details>
+
+<!-- adoption information-->
+:steam_locomotive: If you're seeing this message and your PR is from a branch that doesn't have check-spelling,
+please merge to your PR's base branch to get the version configured for your repository.

.github/actions/spelling-data/allow.txt

@@ -2,3 +2,4 @@ github
 https
 ssh
 ubuntu
+workarounds