Add details about how to retrieve ZIM file

docker/README.md

@@ -4,53 +4,57 @@ without having to install all dependencies. You just need a working
 
 ## Standalone
 
-MWoffliner requires a [Redis](http://www.redis.io) server to run.
+MWoffliner requires a [Redis](https://www.redis.io) server to run.
 
-For convenience purpose, MWoffliner image bundles a redis server launched in the background.
+For convenience purpose, MWoffliner image bundles a Redis daemon launched in the background.
 
-This bundled redis server is configured to be used only through a unix socket and to work exclusively from memory (no writes to disk).
+This bundled Redis daemon is configured to be used only through a unix socket and to work exclusively from memory (no writes to disk).
 
-Use of this bundled server is transparent as `mwoffliner` command is aliased to `mwoffliner --redis /dev/shm/redis.sock`. 
+Use of this bundled server is transparent as `mwoffliner` command is aliased to `mwoffliner --redis /dev/shm/redis.sock`.
 
-``` sh
-docker run -ti ghcr.io/openzim/mwoffliner mwoffliner --help
+To run the following examples, you need first to create a local `out`
+directory in you current directory. Created ZIM files will be written
+there.
+
+```sh
+docker run --volume=$(pwd)/out:/out -ti ghcr.io/openzim/mwoffliner mwoffliner --help
 ```
 
-## With dedicated redis
+## With dedicated Redis
 
 You can also use a dedicated redis container with MWoffliner.
 
 Run a Redis docker container with:
 
-```
-$docker run --name=redis -d redis
+```sh
+docker run --volume=$(pwd)/out:/out --name=redis -d redis
 ```
 
 ... and then run the moffliner interactively (remember to specify `--redis` in command):
 
-```
-$docker run --link=redis:redis --name=mwoffliner -ti ghcr.io/openzim/mwoffliner
+```sh
+$docker run --volume=$(pwd)/out:/out --link=redis:redis --name=mwoffliner -ti ghcr.io/openzim/mwoffliner
 ```
 
 ... or non-interactively, directly with a command line (this is an
 example, the second line is the mwoffliner command itself):
 
-```
-docker run --link=redis:redis --name=mwoffliner -e REDIS="redis://redis" ghcr.io/openzim/mwoffliner \
+```sh
+docker run --volume=$(pwd)/out:/out --link=redis:redis --name=mwoffliner -e REDIS="redis://redis" ghcr.io/openzim/mwoffliner \
        mwoffliner --verbose --mwUrl=https://en.wikipedia.org/ --adminEmail=foo@bar.net
 ```
 
 ## With Docker compose
 
 This allows to run both, Redis & MWoffliner, containers simultaneously:
 
-```
+```sh
 docker-compose --file docker-compose.yml run mwoffliner
 ```
 
 ## Build the Docker image
 
 Run from the repository root:
-```
+```sh
 docker build . -f docker/Dockerfile -t ghcr.io/openzim/mwoffliner
 ```