Urgent fix for crazy docs error on volumes.

Elaborate on the volumes example to prevent confusion.

Update: Amend the example so it is executable by the reader.
This includes fixing the erring "/var/logs" statement with "/var/log".

Update: Fix sentence structuring to better suit the 80chrs. limit.

Docker-DCO-1.1-Signed-off-by: O.S. Tezer <ostezer@gmail.com> (github: ostezer)