updated docs with new uninstall option

Author: erinxocon

docs/basics.rst

@@ -139,7 +139,7 @@ Create a Pipfile.lock from the installed versions:
 Install from that Pipfile.lock:
 
     $ pipenv install --ignore-pipfile
-    
+
 
 .. _initialization:
 
@@ -270,11 +270,14 @@ $ pipenv uninstall
 //////////////////
 
 ``$ pipenv uninstall`` supports all of the parameters in `pipenv install <#pipenv-install>`_,
-as well as one additonal, ``--all``.
+as well as two additonal options, ``--all`` and ``--all-dev``.
 
     - ``--all`` — This parameter will purge all files from the virtual environment,
       but leave the Pipfile untouched.
 
+    - ``--all-dev`` — This parameter will remove all of the development packages from
+      the virtual environment, and remove them from the Pipfile.
+
 
 .. _pipenv_lock: