Document Actions inline expectations test API

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

Author: redsun82

actions/ql/lib/codeql/actions/test/internal/InlineExpectationsTestImpl.qll

@@ -2,10 +2,13 @@ private import codeql.Locations as L
 private import codeql.actions.ast.internal.Yaml
 private import codeql.util.test.InlineExpectationsTest
 
+/** Provides the Actions implementation of inline expectation parsing. */
 module Impl implements InlineExpectationsTestSig {
+  /** A class representing YAML comments that may contain inline expectations. */
   class ExpectationComment extends YamlNode {
     ExpectationComment() { this.toString().matches("%$ %") }
 
+    /** Gets the contents of this comment, starting at the inline expectation marker (`$`). */
     string getContents() { result = this.toString().regexpCapture(".*(\\$ .*)", 1) }
   }