doc: improve developer guide doc

Mention that the virtual environment's default Python version should be
Python 2.7.

Signed-off-by: Rishabh Dave <ridave@redhat.com>

diff --git a/doc/dev/developer_guide/index.rst b/doc/dev/developer_guide/index.rst
index 8be91c0e4c24a6a0cae1f4800856fde416a3139b..aee3d403f78340e062c1b04cbb09663aec72a935 100644 (file)
--- a/doc/dev/developer_guide/index.rst
+++ b/doc/dev/developer_guide/index.rst
@@ -1589,14 +1589,14 @@ using `vstart_runner.py`_. To do that, you'd need `teuthology`_ installed::
 
     $ git clone https://github.com/ceph/teuthology
     $ cd teuthology/
-    $ virtualenv ./venv
+    $ virtualenv -p python2.7 ./venv
     $ source venv/bin/activate
     $ pip install --upgrade pip
     $ pip install -r requirements.txt
     $ python setup.py develop
     $ deactivate
 
-.. note:: The pip command above is pip2, not pip3.
+.. note:: The pip command above is pip2, not pip3; run ``pip --version``.
 
 The above steps installs teuthology in a virtual environment. Before running
 a test locally, build Ceph successfully from the source (refer