Merge pull request #1596 from rust-lang/Kobzol-patch-1

Add missing command in site README

Author: Kobzol

site/README.md

@@ -20,6 +20,7 @@ You can build the website in multiple ways:
   
   # Build frontend
   $ cd site/frontend
+  $ npm install
   $ npm run build
   
   # Build website binary
@@ -30,6 +31,8 @@ You can build the website in multiple ways:
   seconds to 1; this is on the production database and smaller data sets are
   likely to load considerably faster.
 
+For more information about working with the frontend, see [this README](frontend/README.md).
+
 ## Launching
 
 If you've collected data locally, you will likely want to point the site at a