doc: datamodel: link to the glossary

We linked from the glossary to the data model page in the last commit.
It can also be useful to link the other way for readers who might want
to reference more terminology.

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

Documentation/gitdatamodel.adoc

@@ -300,6 +300,10 @@ $ git reflog main --date=iso --no-decorate
 4ccb6d7 main@{2025-09-29 15:16:48 -0400}: commit (initial): Initial commit
 ----
 
+SEE ALSO
+--------
+linkgit:gitglossary[7]
+
 GIT
 ---
 Part of the linkgit:git[1] suite