Minor clarifications to git-filter-branch usage and doc

- Remove "DESTBRANCH" from usage, as it rewrites the branches given.
- Remove an = from an example usage, as the script doesn't understand
it.

Signed-off-by: Brian Gernhardt <benji@silverinsanity.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/git-filter-branch.txt

@@ -120,7 +120,7 @@ have all of them as parents.
 	tag name is expected on standard output.
 +
 The original tags are not deleted, but can be overwritten;
-use "--tag-name-filter=cat" to simply update the tags.  In this
+use "--tag-name-filter cat" to simply update the tags.  In this
 case, be very careful and make sure you have the old tags
 backed up in case the conversion has run afoul.
 +

git-filter-branch.sh

@@ -8,7 +8,7 @@
 # a new branch. You can specify a number of filters to modify the commits,
 # files and trees.
 
-USAGE="git-filter-branch [-d TEMPDIR] [FILTERS] DESTBRANCH [REV-RANGE]"
+USAGE="git-filter-branch [-d TEMPDIR] [FILTERS] [REV-RANGE]"
 . git-sh-setup
 
 warn () {