Fix: Add property annotations to class-level docblock

Author: localheinz

src/RequestTrait.php

@@ -23,6 +23,10 @@
  * the enviornment. As such, this trait exists to provide the common code
  * between both client-side and server-side requests, and each can then
  * use the headers functionality required by their implementations.
+ *
+ * @property array $headers
+ * @property array $headerNames
+ * @property StreamInterface $stream
  */
 trait RequestTrait
 {