Change the docs to suggest .venv instead of venv

Author: ziebam

docs/html/development/getting-started.rst

@@ -42,17 +42,17 @@ You can then invoke your local source tree pip normally.
 
     .. code-block:: shell
 
-        virtualenv venv # You can also use "python -m venv venv" from python3.3+
-        source venv/bin/activate
+        virtualenv .venv # You can also use "python -m venv .venv" from python3.3+
+        source .venv/bin/activate
         python -m pip install -e .
         python -m pip --version
 
 .. tab:: Windows
 
     .. code-block:: shell
 
-        virtualenv venv # You can also use "py -m venv venv" from python3.3+
-        venv\Scripts\activate
+        virtualenv .venv # You can also use "py -m venv .venv" from python3.3+
+        .venv\Scripts\activate
         py -m pip install -e .
         py -m pip --version