git-worktree.txt: link to man pages when citing other Git commands

When citing other Git commands, rather than merely formatting them with
a fixed-width typeface, improve the reader experience by linking to them
directly via `linkgit:`.

Suggested-by: Martin Ågren <martin.agren@gmail.com>
Signed-off-by: Eric Sunshine <sunshine@sunshineco.com>
Reviewed-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Author: sunshineco

Documentation/git-worktree.txt

@@ -25,8 +25,9 @@ Manage multiple working trees attached to the same repository.
 A git repository can support multiple working trees, allowing you to check
 out more than one branch at a time.  With `git worktree add` a new working
 tree is associated with the repository.  This new working tree is called a
-"linked working tree" as opposed to the "main working tree" prepared by `git
-init` or `git clone`.  A repository has one main working tree (if it's not a
+"linked working tree" as opposed to the "main working tree" prepared by
+linkgit:git-init[1] or linkgit:git-clone[1].
+A repository has one main working tree (if it's not a
 bare repository) and zero or more linked working trees. When you are done
 with a linked working tree, remove it with `git worktree remove`.