[PATCH] Documentation: filter-branch env-filter example

["Tadeusz Andrzej Kadłubowski" <yess@hell.org.pl>]

filter-branch --env-filter example that shows how to change the email address
in all commits by a certain developer.
---
 Documentation/git-filter-branch.txt | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/Documentation/git-filter-branch.txt b/Documentation/git-filter-branch.txt
index dfd12c9..2664cec 100644
--- a/Documentation/git-filter-branch.txt
+++ b/Documentation/git-filter-branch.txt
@@ -329,6 +329,19 @@ git filter-branch --msg-filter '
 ' HEAD~10..HEAD
 --------------------------------------------------------

+You can modify committer/author personal information using `--env-filter`.
+For example, to update some developer's email address use this command:
+
+--------------------------------------------------------
+git filter-branch --env-filter '
+	if [ $GIT_AUTHOR_EMAIL = john@old.example.com ]
+	then
+		GIT_AUTHOR_EMAIL=john@new.example.com
+	fi
+	export GIT_AUTHOR_EMAIL
+' -- --all
+--------------------------------------------------------
+
 To restrict rewriting to only part of the history, specify a revision
 range in addition to the new branch name.  The new branch name will
 point to the top-most revision that a 'git rev-list' of this range
-- 
1.7.11.7