doc: maintenance: fix linkgit syntax

Signed-off-by: Kristoffer Haugsbakk <code@khaugsbakk.name>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Author: LemmingAvalanche

Documentation/git-maintenance.adoc

@@ -172,7 +172,7 @@ rerere-gc::
 
 worktree-prune::
 	The `worktree-prune` task deletes stale or broken worktrees. See
-	linkit:git-worktree[1] for more information.
+	linkgit:git-worktree[1] for more information.
 
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