[PATCH v2 1/3] git-checkout.txt: document -d short option for --detach

`git checkout` learned -d as short option for --detach in 163e3b2975
(switch: add short option for --detach, 2019-03-29) but the
documentation was never updated to reflect the change.

Signed-off-by: Eric Sunshine <redacted>
---
 Documentation/git-checkout.txt | 1 +
 1 file changed, 1 insertion(+)

diff --git a/Documentation/git-checkout.txt b/Documentation/git-checkout.txt
index 5b697eee1b..afa5c11fd3 100644
--- a/Documentation/git-checkout.txt
+++ b/Documentation/git-checkout.txt

@@ -198,6 +198,7 @@ Use `--no-guess` to disable this.
 	Create the new branch's reflog; see linkgit:git-branch[1] for
 	details.
 
+-d::
 --detach::
 	Rather than checking out a branch to work on it, check out a
 	commit for inspection and discardable experiments.

-- 
2.28.0.618.gf4bc123cb7