Update content.md

Fixed the documentation so that the H2 database is properly persisted through restarts (previously was lost each time container was destroyed - https://github.com/geonetwork/docker-geonetwork/issues/12 )

geonetwork/content.md

@@ -32,24 +32,24 @@ $ docker run --name some-%%REPO%% -d -p 8080:8080 %%IMAGE%%
 
 Then, if you are running docker on Linux, you may access geonetwork at http://localhost:8080/geonetwork. Otherwise, replace `localhost` by the address of your docker machine.
 
-## Set the data directory
+## Set the data directory and H2 db file
 
-The data directory is the location on the file system where the catalog stores much of its custom configuration and uploaded files. It is also where it stores a number of support files, used for various purposes (e.g.: Lucene index, spatial index, thumbnails).
+The data directory is the location on the file system where the catalog stores much of its custom configuration and uploaded files. It is also where it stores a number of support files, used for various purposes (e.g.: Lucene index, spatial index, thumbnails). The default variant also uses a local H2 database to store the metadata catalog itself.
 
-By default, geonetwork sets the data directory on `/usr/local/tomcat/webapps/geonetwork/WEB-INF/data`, but you may override this value by injecting an environment variable into the container: - `-e DATA_DIR=...` (defaults to `/usr/local/tomcat/webapps/geonetwork/WEB-INF/data`)
+By default, geonetwork sets the data directory on `/usr/local/tomcat/webapps/geonetwork/WEB-INF/data` and H2 database file to the tomcat bin dir `/usr/local/tomcat/gn.h2.db`, but you may override these values by injecting environment variables into the container: - `-e DATA_DIR=...` (defaults to `/usr/local/tomcat/webapps/geonetwork/WEB-INF/data`) and `-e GEONETWORK_DB_NAME=...` (defaults to `gn` which sets up database `gn.h2.db` in tomcat bin dir `/usr/local/tomcat`)
 
-For instance, to set the data directory to `/var/lib/geonetwork_data`:
+## Persisting data
+
+To set the data directory to `/var/lib/geonetwork/data` and H2 database file to `/var/lib/geonetwork/db/gn.h2.db` so they both persist through restarts:
 
 ```console
-$ docker run --name some-%%REPO%% -d -p 8080:8080 -e DATA_DIR=/var/lib/geonetwork_data %%IMAGE%%
+$ docker run --name some-%%REPO%% -d -p 8080:8080 -e DATA_DIR=/var/lib/geonetwork/data -e GEONETWORK_DB_NAME=/var/lib/geonetwork/db/gn %%IMAGE%%
 ```
 
-## Persist data
-
-If you want the data directory to live beyond restarts, or even destruction of the container, you can mount a directory from the docker engine's host into the container. - `-v /host/path:/path/to/data/directory`. For instance this, will mount the host directory `/host/geonetwork-docker` into `/var/lib/geonetwork_data` on the container:
+If you want the data directory to live beyond restarts, or even destruction of the container, you can mount a directory from the docker engine's host into the container. - `-v /host/path:/path/to/data/directory`. For instance this, will mount the host directory `/host/geonetwork-docker` into `/var/lib/geonetwork` on the container:
 
 ```console
-$ docker run --name some-%%REPO%% -d -p 8080:8080 -e DATA_DIR=/var/lib/geonetwork_data -v /host/geonetwork-docker:/var/lib/geonetwork_data %%IMAGE%%
+$ docker run --name some-%%REPO%% -d -p 8080:8080 -e DATA_DIR=/var/lib/geonetwork/data -e GEONETWORK_DB_NAME=/var/lib/geonetwork/db/gn -v /host/geonetwork-docker:/var/lib/geonetwork %%IMAGE%%
 ```
 
 ## %%STACK%%