Small update to guid_gce.rst, says 'project-name', should be 'project_id'.

docsite/rst/guide_gce.rst

@@ -77,7 +77,7 @@ Create a file ``secrets.py`` looking like following, and put it in some folder w
 .. code-block:: python
 
     GCE_PARAMS = ('i...@project.googleusercontent.com', '/path/to/project.pem')
-    GCE_KEYWORD_PARAMS = {'project': 'project-name'}
+    GCE_KEYWORD_PARAMS = {'project': 'project_id'}
 
 Now the modules can be used as above, but the account information can be omitted.