Add .clang-tidy filename for YAML (#3767)

.clang-tidy is the filename used for clang-tidy's configuration file.
clang-tidy is a clang-based C++ "linter" tool. For more info, see:
https://clang.llvm.org/extra/clang-tidy/

lib/linguist/languages.yml

@@ -5060,6 +5060,7 @@ YAML:
   - ".yml.mysql"
   filenames:
   - ".clang-format"
+  - ".clang-tidy"
   ace_mode: yaml
   codemirror_mode: yaml
   codemirror_mime_type: text/x-yaml