hook: add a simple first example

Add a simple example that replaces an outdated example
that was removed. This ensures that there's at the least
a simple example that illustrates what could be done
using the hook just by enabling it.

Also, update the documentation.

Signed-off-by: Kaartic Sivaraam <kaarticsivaraam91196@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/githooks.txt

@@ -121,6 +121,9 @@ it is not suppressed by the `--no-verify` option.  A non-zero exit
 means a failure of the hook and aborts the commit.  It should not
 be used as replacement for pre-commit hook.
 
+The sample `prepare-commit-msg` hook that comes with Git removes the
+help message found in the commented portion of the commit template.
+
 commit-msg
 ~~~~~~~~~~
 

templates/hooks--prepare-commit-msg.sample

@@ -9,20 +9,23 @@
 #
 # To enable this hook, rename this file to "prepare-commit-msg".
 
-# This hook includes two examples.
+# This hook includes three examples. The first one removes the
+# "# Please enter the commit message..." help message.
 #
-# The first includes the output of "git diff --name-status -r"
+# The second includes the output of "git diff --name-status -r"
 # into the message, just before the "git status" output.  It is
 # commented because it doesn't cope with --amend or with squashed
 # commits.
 #
-# The second example adds a Signed-off-by line to the message, that can
+# The third example adds a Signed-off-by line to the message, that can
 # still be edited.  This is rarely a good idea.
 
 COMMIT_MSG_FILE=$1
 COMMIT_SOURCE=$2
 SHA1=$3
 
+@PERL_PATH@ -i.bak -ne 'print unless(m/^. Please enter the commit message/..m/^#$/)' "$COMMIT_MSG_FILE"
+
 # case "$COMMIT_SOURCE,$SHA1" in
 #  ,|template,)
 #    @PERL_PATH@ -i.bak -pe '