Documentation/git-worktree: fix duplicated 'from'

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Acked-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Author: pks-t

Documentation/git-worktree.txt

@@ -124,7 +124,7 @@ thumb is do not make any assumption about whether a path belongs to
 $GIT_DIR or $GIT_COMMON_DIR when you need to directly access something
 inside $GIT_DIR. Use `git rev-parse --git-path` to get the final path.
 
-To prevent a $GIT_DIR/worktrees entry from from being pruned (which
+To prevent a $GIT_DIR/worktrees entry from being pruned (which
 can be useful in some situations, such as when the
 entry's working tree is stored on a portable device), add a file named
 'locked' to the entry's directory. The file contains the reason in