Documentation update: use git branch -d foo where applicable

This updates documentation to use git branch -d foo in favour of
rm .git/refs/heads/foo

Signed-off-by: Kai Ruemmler <kai.ruemmler@gmx.net>
Signed-off-by: Junio C Hamano <junkio@cox.net>

Documentation/howto/rebase-and-edit.txt

@@ -63,7 +63,7 @@ And then, you can just remove the broken branch if you decide you really
 don't want it:
 
 	# remove 'broken' branch
-	rm .git/refs/heads/broken
+	git branch -d broken
 
 	# Prune old objects if you're really really sure
 	git prune

Documentation/howto/revert-branch-rebase.txt

@@ -153,7 +153,8 @@ Everything is in the good order.  I do not need the temporary branch
 nor tag anymore, so remove them:
 
 ------------------------------------------------
-$ rm -f .git/refs/tags/pu-anchor .git/refs/heads/revert-c99
+$ rm -f .git/refs/tags/pu-anchor 
+$ git branch -d revert-c99
 ------------------------------------------------
 
 It was an emergency fix, so we might as well merge it into the

Documentation/howto/using-topic-branches.txt

@@ -166,7 +166,7 @@ output from:
 
 is empty.  At this point the branch can be deleted:
 
- $ rm .git/refs/heads/branchname
+ $ git branch -d branchname
 
 Some changes are so trivial that it is not necessary to create a separate
 branch and then merge into each of the test and release branches.  For