add note to docs and readme on installing from source

Author: quasiben

README.rst

@@ -23,4 +23,27 @@ The primary use cases are:
 
 
 `The documentation <https://jupyter-server-proxy.readthedocs.io/>`_
-contains information on installation & usage.
+contains information on installation & usage.
+
+====================
+Install
+====================
+
+pip
+---
+
+pip install jupyter-server-proxy
+
+conda
+-----
+
+conda install jupyter-server-proxy -c conda-forge
+
+src
+---
+
+pip install .
+
+**Note:** if installing from source in editable mode: ``setup.py develop/pip install -e``, please explicitly install the server extensions:
+
+``jupyter serverextension enable --sys-prefix jupyter_server_proxy``

docs/install.rst

@@ -11,6 +11,12 @@ Jupyter Server Proxy can be installed with ``pip``. You must install
    pip install jupyter-server-proxy
 
 
+If using ``pip install -e`` please install the server extension explicitly:
+
+.. code:: bash
+
+   jupyter serverextension enable --sys-prefix jupyter_server_proxy
+
 If you have multiple virtualenvs or conda environments, you
 must install ``jupyter-server-proxy`` into the same environment
-your notebook is running from, rather than where your kernels are.
+your notebook is running from, rather than where your kernels are.