docs(@angular/cli): alias (-pc) for proxy-config

Author: imcotton

docs/documentation/serve.md

@@ -244,7 +244,7 @@ All the build Options are available in serve, below are the additional options.
 <details>
   <summary>proxy-config</summary>
   <p>
-    <code>--proxy-config</code>
+    <code>--proxy-config</code> (aliases: <code>-pc</code>)
   </p>
   <p>
     Use a <a href="https://github.com/angular/angular-cli/blob/master/docs/documentation/stories/proxy.md">proxy</a> configuration file to send some requests to a backend server rather than the webpack dev server.