Merge pull request keras-team#1645 from oraac/master

added more detail to the building documentation instructions

Author: fchollet

docs/README.md

@@ -8,4 +8,5 @@ Our documentation uses extended Markdown, as implemented by [MkDocs](http://mkdo
 - install MkDocs: `pip install mkdocs`
 - `cd` to the `docs/` folder and run:
     - `python autogen.py`
-    - `mkdocs serve`
+    - `mkdocs serve`    # Starts a local webserver:  [localhost:8000](localhost:8000)
+    - `mkdocs build`    # Builds a static site in "site" directory