translations:fixes for string messages
docs: git workflow additions and corrections

* Adds explicit requirement for empty lines between commit message body list
items.

* Changes headline length requirement to strict 50 characters.

* Breaks long lines.

* Adds note on using vim as commit message editor.

* Adds a more complete commit message example.

Signed-off-by: Adrian-Tudor Panescu <adrian.tudor.panescu@cern.ch>