[PATCH] doc: update advice about other implementations' v4 index support

[scottworley@scottworley.com]

From: Scott Worley <scottworley@scottworley.com>

Signed-off-by: Scott Worley <scottworley@scottworley.com>
---
 Documentation/git-update-index.txt | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/Documentation/git-update-index.txt b/Documentation/git-update-index.txt
index 2853f168d9..e8eca5dadf 100644
--- a/Documentation/git-update-index.txt
+++ b/Documentation/git-update-index.txt
@@ -166,9 +166,10 @@ you will need to handle the situation manually.
 +
 Version 4 performs a simple pathname compression that reduces index
 size by 30%-50% on large repositories, which results in faster load
-time. Version 4 is relatively young (first released in 1.8.0 in
-October 2012). Other Git implementations such as JGit and libgit2
-may not support it yet.
+time. Version 4 is relatively young (first released in git 1.8.0 in
+October 2012, supported in libgit2 0.24.4 from December 2016, go-git
+4.0.0 from January 2018, and jgit 5.9.0 from September 2020). Other
+Git implementations such as Dulwich may not support it yet.
 
 -z::
 	Only meaningful with `--stdin` or `--index-info`; paths are
-- 
2.29.3