Use yamllint configuration file to define the file names to check

Because there are multiple popular file types that use YAML markup, but not the standardized file extension, I previously
was using `find` to discover all the files to check with yamllint. However, it turns out that this can be defined in the
yamllint configuration file. In addition to being less prone to breakage and providing a more minimal workflow, this also
means that contributors who run yamllint locally will get the same results as the CI.

Author: per1234

.github/workflows/check-yaml.yml

@@ -59,42 +59,20 @@ jobs:
             # yamllint's "github" output type produces annotated diffs, but is not useful to humans reading the log.
             format: github
             # The other matrix job is used to set the result, so this job is configured to always pass.
-            fail-command: "true"
+            continue-on-error: true
           - name: Check formatting
             # yamllint's "colored" output type is most suitable for humans reading the log.
             format: colored
-            fail-command: "false"
+            continue-on-error: false
 
     steps:
       - name: Checkout repository
         uses: actions/checkout@v2
 
       - name: Check YAML
         # yamllint's "colored" output type is useful for humans reading the log.
+        continue-on-error: ${{ matrix.configuration.continue-on-error }}
         run: |
-          find . \
-            -path './.git' -prune -or \
-            \( \
-              \( \
-                -name '.clang-format' -or \
-                -name '.clang-tidy' -or \
-                -name '.gemrc' -or \
-                -name '*.yml' -or \
-                -name '*.mir' -or \
-                -name '*.reek' -or \
-                -name '*.rviz' -or \
-                -name '*.sublime-syntax' -or \
-                -name '*.syntax' -or \
-                -name '*.yaml' -or \
-                -name '*.yaml-tmlanguage' -or \
-                -name '*.yaml.sed' -or \
-                -name '*.yaml.mysql' \
-              \) \
-              -and -type f \
-            \) \
-            -exec \
-              yamllint \
-                --format ${{ matrix.configuration.format }} \
-                '{}' + \
-                || \
-                ${{ matrix.configuration.fail-command }}
+          yamllint \
+            --format ${{ matrix.configuration.format }} \
+            .

.yamllint.yml

@@ -50,3 +50,24 @@ rules:
       - "false"
       - "on" # Used by GitHub Actions as a workflow key.
     check-keys: true
+
+yaml-files:
+  # Source: https://github.com/ikatyang/linguist-languages/blob/master/data/YAML.json (used by Prettier)
+  - ".clang-format"
+  - ".clang-tidy"
+  - ".gemrc"
+  - ".yamllint"
+  - "glide.lock"
+  - "*.yml"
+  - "*.mir"
+  - "*.reek"
+  - "*.rviz"
+  - "*.sublime-syntax"
+  - "*.syntax"
+  - "*.yaml"
+  - "*.yaml-tmlanguage"
+  - "*.yaml.sed"
+  - "*.yml.mysql"
+
+ignore: |
+  /.git/