[PATCH] doc: explain the impact of stash.index on --autostash options

["D. Ben Knoble" <ben.knoble+github@gmail.com>]

With 9842c0c749 (stash: honor stash.index in apply, pop modes,
2025-09-21) merged in a5d4779e6e (Merge branch 'dk/stash-apply-index',
2025-09-29), we did not advertise the connection between the new config
option stash.index and the implicit use of git-stash via --autostash
(which may also be configured). Do so.

Signed-off-by: D. Ben Knoble <ben.knoble+github@gmail.com>
---

This builds on dk/stash-apply-index from gitster/git and is published at
https://github.com/benknoble/git/tree/stash-apply-index-doc

 Documentation/config/stash.adoc | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/Documentation/config/stash.adoc b/Documentation/config/stash.adoc
index e556105a15..fcb9a4a7a0 100644
--- a/Documentation/config/stash.adoc
+++ b/Documentation/config/stash.adoc
@@ -2,6 +2,10 @@ stash.index::
 	If this is set to true, `git stash apply` and `git stash pop` will
 	behave as if `--index` was supplied. Defaults to false. See the
 	descriptions in linkgit:git-stash[1].
++
+This also affects invocations of linkgit:git-stash[1] via `--autostash` from
+commands like linkgit:git-merge[1], linkgit:git-rebase[1], and
+linkgit:git-pull[1].
 
 stash.showIncludeUntracked::
 	If this is set to true, the `git stash show` command will show

base-commit: 9842c0c7492d2858d64ef81128f7b1f0b38e326b
-- 
2.48.1