Documentation: describe subject more precisely

The discussion of email subject throughout the documentation is
misleading; it indicates that the first line will always become
the subject.  In fact, the subject is generally all lines up until
the first full blank line.

This patch refines that, and makes more use of the concept of a
commit title, with the title being all text up to the first blank line.

Signed-off-by: Jeremy White <jwhite@codeweavers.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 5 insertions, 3 deletions

diff --git a/Documentation/gittutorial.txt b/Documentation/gittutorial.txt
index dee050567e..f1cb6f3be6 100644
--- a/Documentation/gittutorial.txt
+++ b/Documentation/gittutorial.txt
@@ -139,9 +139,11 @@ them to the index, and commit, all in one step.
 A note on commit messages: Though not required, it's a good idea to
 begin the commit message with a single short (less than 50 character)
 line summarizing the change, followed by a blank line and then a more
-thorough description.  Tools that turn commits into email, for
-example, use the first line on the Subject: line and the rest of the
-commit in the body.
+thorough description. The text up to the first blank line in a commit
+message is treated as the commit title, and that title is used
+throughout git.  For example, linkgit:git-format-patch[1] turns a
+commit into email, and it uses the title on the Subject line and the
+rest of the commit in the body.
 
 Git tracks content not files
 ----------------------------