message: add a comments for regex
diff: @@ -304,6 +304,8 @@ export class AjaxMonitor implements ITelemetryPlugin, IDependenciesPlugin, IInst
  if (this._config.enableResponseHeaderTracking) {
  var headers = xhr.getAllResponseHeaders();
  if (headers) {
  + // xhr.getAllResponseHeaders() method returns all the response headers, separated by CRLF, as a string or null
  + // the regex converts the header string into an array of individual headers
  var arr = headers.trim().split(/[\r\n]+/);
  var responseHeaderMap = {};
  arr.forEach(function (line) {
  