message: docs(forms): clarify the pattern validator behavior
  PR Close
diff: @@ -273,8 +273,12 @@ export class Validators {
  /**
  * @description
  * Validator that requires the control's value to match a regex pattern. This validator is also
  - * provided
  - * by default if you use the HTML5 `pattern` attribute.
  + * provided by default if you use the HTML5 `pattern` attribute.
  + *
  + * Note that if a Regexp is provided, the Regexp is used as is to test the values. On the other
  + * hand, if a string is passed, the `^` character is prepended and the `$` character is
  + * appended to the provided string (if not already present), and the resulting regular
  + * expression is used to test the values.
  *
  * @usageNotes
  *
  