Make page title consistent with the others

All other pages, as well as the markdown file, have the verb in
imperative mood.

Signed-off-by: Leandro Lucarella <[email protected]>

Author: llucax

docs/user-guide/start-a-new-project/index.md

@@ -1,4 +1,4 @@
-# Starting a new project
+# Start a new project
 
 ## Install Cookiecutter