Swift: Add qldoc for AutoClosureExpr.

Author: geoffw0

swift/ql/lib/codeql/swift/elements/expr/AutoClosureExpr.qll

@@ -2,8 +2,22 @@ private import codeql.swift.generated.expr.AutoClosureExpr
 private import codeql.swift.elements.stmt.ReturnStmt
 private import codeql.swift.elements.expr.Expr
 
+/**
+ * A Swift autoclosure expression, that is, a closure automatically generated
+ * around an argument when the parameter has the `@autoclosure` attribute. For
+ * example, there is an `AutoClosureExpr` around the value `0` in:
+ * ```
+ * func myFunction(_ expr: @autoclosure () -> Int) {
+ *   ...
+ * }
+ *
+ * myFunction(0)
+ * ```
+ */
 class AutoClosureExpr extends Generated::AutoClosureExpr {
-  /** Gets the implicit return statement generated by this autoclosure expression. */
+  /**
+   * Gets the implicit return statement generated by this autoclosure expression.
+   */
   ReturnStmt getReturn() { result = unique( | | this.getBody().getAnElement()) }
 
   /**