Add info about adding extra nginx config.

README.md

@@ -5,7 +5,35 @@ a collection of containers that will provide automatic reverse proxying
 and SSL termination for other docker containers.
 
 More details will be added here in due course. For now, the full process
-is described in [this blog post](https://www.chameth.com/2016/05/21/docker-automatic-nginx-proxy.html).
+is described in [this blog post](https://www.chameth.com/2016/05/21/docker-automatic-nginx-proxy).
+
+## Adding extra config to Nginx
+
+Out of the box, the Nginx server will only handle HTTPS requests,
+with a very minimal config. The [extra](extra/) directory contains
+some additional configuration snippets which may potentially be
+useful.
+
+Once you have the services running, you can copy additional config
+using the cp command:
+
+```
+docker cp file.conf autoproxy_nginx:/etc/nginx/conf.d/
+```
+
+The following config files are available in the extra directory:
+
+ * [hsts.conf](extra/hsts.conf) - enables HTTP Strict Transport Security for
+   all HTTPS hosts. HSTS tells browsers that they should only ever request
+   pages on that domain over HTTPS.
+ * [redirect-http.conf](extra/redirect-http.conf) - adds a default HTTP
+   server that redirects all traffic to HTTPS.
+ * [security.conf](extra/security.conf) - enables some security best
+   practices: stops Nginx reporting its version, and adds headers to
+   help mitigate clickjacking, content type hijacking, and XSS.
+ * [ssl.conf](extra/ssl.conf) - adds extra SSL configuration options to
+   disable old protocols and ciphers, enable stapling, etc. This will prevent
+   access from older browsers and operating systems!
 
 ## Hosting static content
 
@@ -19,7 +47,6 @@ file like so:
 
 ```yaml
 ---
-
 version: '2'
 
 services: