Add documentation for EmptyLineBetweenBlocks

Forgot to do this as part of 8acdc4b.

Change-Id: Iec4905adfcb86d097388d976eac7401f6bbc330a
Reviewed-on: https://gerrit.causes.com/32426
Tested-by: jenkins <jenkins@causes.com>
Reviewed-by: Shane da Silva <shane@causes.com>