Restructure documentation for git-merge-base.
Restructure documentation for git-merge-base.

Restructure the text of git-merge-base to better explain more clearly
the different modes of operation.

Signed-off-by: Vincent van Ravesteijn <1c466654e4be28a1d0eae862fbfcbb6a3fd67387@lyx.org>
Signed-off-by: Junio C Hamano <a6723cc3f76163bf7adb636a73ac3b0ceb3e6b9b@pobox.com>

destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git