docs(setup): note that npm start fails in Bash for Windows (#3065)

Author: wardbell

public/docs/ts/latest/guide/setup.jade

@@ -45,6 +45,10 @@ code-example(language="sh" class="code-shell").
   !{_npm} !{_install}
   !{_npm} !{_start}
 
+.alert.is-important
+  :marked
+    `npm start` fails in _Bash for Windows_ which does not support networking to servers as of January, 2017.
+
 a#download
 :marked
   ### Download
@@ -56,6 +60,10 @@ code-example(language="sh" class="code-shell").
   !{_npm} !{_install}
   !{_npm} !{_start}
 
+.alert.is-important
+  :marked
+    `npm start` fails in _Bash for Windows_ which does not support networking to servers as of January, 2017.
+
 .l-main-section#seed
 :marked
   ## What's in the QuickStart seed?