message: docs: remove repeated word
diff: @@ -957,7 +957,7 @@ message HeaderMatcher {
  string suffix_match = 10 [(validate.rules).string.min_bytes = 1];
  }
  - // If specified, the match result will be inverted before before checking. Defaults to false.
  + // If specified, the match result will be inverted before checking. Defaults to false.
  //
  // Examples:
  //
  