Update README.md

README.md

@@ -19,7 +19,7 @@
 
 The dockerfile has been revamped to make is easier to get started, by default the base image selected in 5 which will pull in the latest v5 stable image.
 
-```
+```bash
 git clone https://github.com/invoiceninja/dockerfiles.git
 cd dockerfiles
 ```
@@ -32,6 +32,7 @@ APP_KEY=<insert your generated key in here>
 APP_DEBUG=true
 MULTI_DB_ENABLED=false
 DB_HOST1=db
+DB_PORT1=3306
 DB_USERNAME1=ninja
 DB_PASSWORD1=ninja
 DB_DATABASE1=ninja
@@ -52,6 +53,18 @@ From the terminal run
 
 ```sudo chown -R 1500:1500 docker/app```
 
+## Updating the image when using `docker-compose`
+
+As `docker-compose` does not support any form of version control, this git provide updates to `docker-compose.yml` directly. 
+
+To upgrade to a newer release image, please make sure to update the `docker-compose.yml` first by running
+
+```bash
+git pull
+```
+
+You may need to manually merge any changes that cannot be merged automatically by git.
+
 ### Note for people running the container locally on their PC ###
 
 If you are running the container locally, then the container will need to resolve the host, to support this you will want to insert your LAN IP address and the host name in the hosts file located in ```config/hosts```
@@ -74,6 +87,3 @@ All that is left to do now is bring up the container
 ## Support
 
 If you discover a bug, please create and issue, if you query is general in nature please visit us on our [Forum ](https://forum.invoiceninja.com/)
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