[PATCH] Update git rebase documentation to clarify HEAD behavior

The first few paragraphs in the git-rebase.txt documentation lay out the steps git takes during a rebase:
1. everything from `<upstream>..HEAD` is saved to a temporary area
2. `HEAD` is set to `<upstream>`
3. the changes held in the temporary area are applied one by one in order on top of the new `HEAD`

The second step was described using the phrase `The current branch is reset to <upstream>`, which is true (because `HEAD` == current branch), but not clear.
---
 Documentation/git-rebase.txt | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Documentation/git-rebase.txt b/Documentation/git-rebase.txt
index de222c8..c47ca11 100644
--- a/Documentation/git-rebase.txt
+++ b/Documentation/git-rebase.txt

@@ -33,7 +33,7 @@ of commits that would be shown by `git log <upstream>..HEAD`; or by
 description on `--fork-point` below); or by `git log HEAD`, if the
 `--root` option is specified.
 
-The current branch is reset to <upstream>, or <newbase> if the
+HEAD is reset to <upstream>, or <newbase> if the
 --onto option was supplied.  This has the exact same effect as
 `git reset --hard <upstream>` (or <newbase>).  ORIG_HEAD is set
 to point at the tip of the branch before the reset.

--

https://github.com/git/git/pull/301