Fix missing 'does' in man-page for 'git checkout'

Reported-by: Rainer Standke <rainer.standke@krankikom.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/git-checkout.txt

@@ -45,14 +45,14 @@ successful.
 
 'git checkout' [--patch] [<tree-ish>] [--] <pathspec>...::
 
-	When <paths> or `--patch` are given, 'git checkout' *not* switch
+	When <paths> or `--patch` are given, 'git checkout' does *not*
-	branches.  It updates the named paths in the working tree from
+	switch branches.  It updates the named paths in the working tree
-	the index file or from a named <tree-ish> (most often a commit).  In
+	from the index file or from a named <tree-ish> (most often a
-	this case, the `-b` and `--track` options are meaningless and giving
+	commit).  In this case, the `-b` and `--track` options are
-	either of them results in an error. The <tree-ish> argument can be
+	meaningless and giving either of them results in an error.  The
-	used to specify a specific tree-ish (i.e. commit, tag or tree)
+	<tree-ish> argument can be used to specify a specific tree-ish
-	to update the index for the given paths before updating the
+	(i.e.  commit, tag or tree) to update the index for the given
-	working tree.
+	paths before updating the working tree.
 +
 The index may contain unmerged entries because of a previous failed merge.
 By default, if you try to check out such an entry from the index, the