[PATCH] Documentation: filter-branch: document how to filter all refs

[Thomas Rast <trast@student.ethz.ch>]

Document the '--' option that can be used to pass rev-list options
(not just arguments), and give an example usage of '-- --all'.

Signed-off-by: Thomas Rast <trast@student.ethz.ch>
---

[This went out to Jan and Junio already, but I forgot to CC the list.
Sorry.]

Somehow I'm imagining this is a FAQ.  Either way, I remember figuring
out this exact example by accident when I first needed it.

 Documentation/git-filter-branch.txt |   13 ++++++++++++-
 1 files changed, 12 insertions(+), 1 deletions(-)

diff --git a/Documentation/git-filter-branch.txt b/Documentation/git-filter-branch.txt
index a518ba6..1f0fcec 100644
--- a/Documentation/git-filter-branch.txt
+++ b/Documentation/git-filter-branch.txt
@@ -13,7 +13,7 @@ SYNOPSIS
 	[--msg-filter <command>] [--commit-filter <command>]
 	[--tag-name-filter <command>] [--subdirectory-filter <directory>]
 	[--original <namespace>] [-d <directory>] [-f | --force]
-	[<rev-list options>...]
+	[--] [<rev-list options>...]
 
 DESCRIPTION
 -----------
@@ -196,6 +196,17 @@ git filter-branch --index-filter 'git rm --cached filename' HEAD
 
 Now, you will get the rewritten history saved in HEAD.
 
+To rewrite the repository to look as if 'foodir/' had been its project
+root, and discard all other history:
+
+-------------------------------------------------------
+git filter-branch --subdirectory-filter foodir -- --all
+-------------------------------------------------------
+
+Thus you can, e.g., turn a library subdirectory into a repository of
+its own.  Note the '--' that separates 'filter-branch' options from
+revision options, and the '--all' to rewrite all branches and tags.
+
 To set a commit (which typically is at the tip of another
 history) to be the parent of the current initial commit, in
 order to paste the other history behind the current history:
-- 
1.6.0.rc1.106.g98a7