Add some information about properly formatted commit messages

It does seem like a lot of github users are not used to good commit
message rules, and may never have used git for a project that actually
cares about good logs and nice summary lines.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

README

@@ -49,3 +49,24 @@ the right to pass it on as an open source patch.
 
 See: http://gerrit.googlecode.com/svn/documentation/2.0/user-signedoffby.html
 
+Also, please write good git commit messages.  A good commit message
+looks like this:
+
+	header line: explaining the commit in one line
+
+	Body of commit message is a few lines of text, explaining things
+	in more detail, possibly giving some background about the issue
+	being fixed, etc etc.
+
+	The body of the commit message can be several paragrahps, and
+	please do proper word-wrap and keep columns shorter than about
+	74 characters or so. That way "git log" will show things
+	nicely even when it's indented.
+
+	Reported-by: whoever-reported-it
+	Signed-off-by: Your Name <youremail@yourhost.com>
+
+where that header line really should be meaningful, and really should be
+just one line.  That header line is what is shown by tools like gitk and
+shortlog, and should summarize the change in one readable line of text,
+independently of the longer explanation.