Update isDefaultThisBinding description

lib/rules/utils/ast-utils.js

@@ -581,14 +581,17 @@ module.exports = {
      *
      * First, this checks the node:
      *
-     * - The function name does not start with uppercase (it's a constructor).
+     * - The function name does not start with uppercase. It's a convention to capitalize the names
+     *   of constructor functions. This check is not performed if `capIsConstructor` is set to `false`.
      * - The function does not have a JSDoc comment that has a @this tag.
      *
      * Next, this checks the location of the node.
      * If the location is below, this judges `this` is valid.
      *
      * - The location is not on an object literal.
-     * - The location is not assigned to a variable which starts with an uppercase letter.
+     * - The location is not assigned to a variable which starts with an uppercase letter. Applies to anonymous
+     *   functions only, as the name of the variable is considered to be the name of the function in this case.
+     *   This check is not performed if `capIsConstructor` is set to `false`.
      * - The location is not on an ES2015 class.
      * - Its `bind`/`call`/`apply` method is not called directly.
      * - The function is not a callback of array methods (such as `.forEach()`) if `thisArg` is given.