docs: add Docker instructions to README.md

README.md

@@ -1,19 +1,26 @@
 # Using website-local-proxy
 
-This is a reverse proxy to handle the port-forwarding of the various locally-hosted Keyman sites. Assuming the corresponding sites already already running, the proxy can be started with the command-line:
+This is a reverse proxy to handle the port-forwarding of the various
+locally-hosted Keyman sites. The proxy can be started with the command-line:
+
 ```bash
 build.sh build start
 ```
 
-If you want the host to use a port other than 80, set the environment variable `KEYMAN_COM_PROXY_PORT` to the port number.
+If you want the host to use a port other than 80, set the environment variable
+`KEYMAN_COM_PROXY_PORT` to the port number.
 
-Once the reverse proxy is started, you can browse to locally hosted Keyman sites like the following:
+Once the reverse proxy is started, you can browse to locally hosted Keyman sites
+like the following:
 * http://api.keyman.com.localhost
 * http://help.keyman.com.localhost
 * http://keyman.com.localhost
 * http://keymanweb.com.localhost
 * http://s.keyman.com.localhost
 
+**Recommended:** Use [shared-sites] to control startup and shutdown of all
+keyman.com sites together.
+
 ## Pre-requisites
 
 - On the host machine, install [Docker](https://docs.docker.com/get-docker/).
@@ -25,3 +32,5 @@ Once the reverse proxy is started, you can browse to locally hosted Keyman sites
 ```
 127.0.0.1       localhost help.keyman.com.localhost api.keyman.com.localhost keyman.com.localhost keymanweb.com.localhost s.keyman.com.localhost
 ```
+
+[shared-sites]: https://github.com/keymanapp/shared-sites