Merge pull request #1847 from yossigo/fix-redis-config-bindmount

Redis: update configuration bindmount example.

redis/content.md

@@ -51,11 +51,13 @@ CMD [ "redis-server", "/usr/local/etc/redis/redis.conf" ]
 Alternatively, you can specify something along the same lines with `docker run` options.
 
 ```console
-$ docker run -v /myredis/conf/redis.conf:/usr/local/etc/redis/redis.conf --name myredis %%IMAGE%% redis-server /usr/local/etc/redis/redis.conf
+$ docker run -v /myredis/conf:/usr/local/etc/redis --name myredis %%IMAGE%% redis-server /usr/local/etc/redis/redis.conf
 ```
 
 Where `/myredis/conf/` is a local directory containing your `redis.conf` file. Using this method means that there is no need for you to have a Dockerfile for your redis container.
 
+The mapped directory should be writable, as depending on the configuration and mode of operation, Redis may need to create additional configuration files or rewrite existing ones.
+
 ## `32bit` variant
 
 This variant is *not* a 32bit image (and will not run on 32bit hardware), but includes Redis compiled as a 32bit binary, especially for users who need the decreased memory requirements associated with that. See ["Using 32 bit instances"](http://redis.io/topics/memory-optimization#using-32-bit-instances) in the Redis documentation for more information.