Basic dev/test setup for separate package subdirectories.

docs/contributing.rst

@@ -26,7 +26,7 @@ Install the development packages:
 
 .. code-block:: shell
 
-   pip install -r requirements.txt -e .[dev,docs,testing]
+   pip install -r requirements.txt -e acme -e .[dev,docs,testing] -e letsencrypt_apache -e letsencrypt_nginx
 
 .. note:: `-e` (short for `--editable`) turns on *editable mode* in
           which any source code changes in the current working

docs/using.rst

@@ -108,7 +108,7 @@ Installation
 .. code-block:: shell
 
    virtualenv --no-site-packages -p python2 venv
-   ./venv/bin/pip install -r requirements.txt .
+   ./venv/bin/pip install -r requirements.txt acme . letsencrypt_apache letsencrypt_nginx
 
 .. warning:: Please do **not** use ``python setup.py install``. Please
              do **not** attempt the installation commands as