Merge pull request #3780 from yakky/feature/installer_docs

Change installer docs

docs/introduction/install_from_scratch.rst

@@ -46,6 +46,12 @@ Django project called ``mysite``::
 
     djangocms -p . mysite
 
+.. warning:: djangocms-installer expects directory ``.`` to be empty at this stage, and will
+             check for this, and will warn if it's not.
+             You can get it to skip the check and go ahead anyway using  the ``-s`` flag;
+             **note that this may overwrite existing files**.
+
+
 Windows users may need to do a little extra to make sure Python files are associated correctly if that doesn't work right away::
 
     assoc .py=Python.file