Fix 'commit-msg' to cite 'CONTRIBUTE'

As suggested in:
http://lists.gnu.org/archive/html/emacs-devel/2015-03/msg00947.html
Also, have the two files match better.
* CONTRIBUTE: Match what's in build-aux/git-hooks/commit-msg.
* build-aux/git-hooks/commit-msg: Mention 'CONTRIBUTE'.

1 files changed, 11 insertions, 5 deletions

diff --git a/CONTRIBUTE b/CONTRIBUTE
index 7c40227b6d9..c72314367a4 100644
--- a/CONTRIBUTE
+++ b/CONTRIBUTE
@@ -37,16 +37,17 @@ specify the actual author; the committer defaults to you.
 When using git, commit messages should use ChangeLog format, with the
 following modifications:
 
-- Add a single short line explaining the change, then an empty line,
-  then unindented ChangeLog entries.
+- Start with a single unindented summary line explaining the change,
+  then an empty line, then unindented ChangeLog entries.
 
   You can use various Emacs functions to ease this process; see (info
   "(emacs)Change Log Commands") or
   http://www.gnu.org/software/emacs/manual/html_node/emacs/Change-Log-Commands.html.
 
-- The summary line is limited to 72 characters (enforced by a commit
-  hook). If you have trouble making that a good summary, add a
-  paragraph below it, before the individual file descriptions.
+- Limit lines in commit messages to 78 characters, unless they consist
+  of a single word of at most 140 characters.  If you have trouble
+  fitting the summary into 78 characters, add a summarizing paragraph
+  below the empty line and before the individual file descriptions.
 
 - If only a single file is changed, the summary line can be the normal
   file first line (starting with the asterisk).  Then there is no
@@ -57,6 +58,11 @@ following modifications:
   the rationale for a change; that can be done in the commit message
   between the summary line and the file entries.
 
+- Commit messages should contain only printable UTF-8 characters.
+
+- Commit messages should not contained the "Signed-off-by:" lines that
+  are used in some other projects.
+
 ** ChangeLog notes
 
 - Emacs generally follows the GNU coding standards when it comes to