[PATCH v1 3/3] read-cache: Add documentation for the post-indexchanged hook

[Ben Peart <peartben@gmail.com>]

From: Kevin Willford <kewillf@microsoft.com>

Document the new post-indexchanged hook with information on when it is
called as well as the flags passed and what each of them mean.

Signed-off-by: Kevin Willford <kewillf@microsoft.com>
Signed-off-by: Ben Peart <benpeart@microsoft.com>
---
 Documentation/githooks.txt | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/Documentation/githooks.txt b/Documentation/githooks.txt
index 959044347e..9349cd8900 100644
--- a/Documentation/githooks.txt
+++ b/Documentation/githooks.txt
@@ -492,6 +492,24 @@ This hook is invoked by `git-p4 submit`. It takes no parameters and nothing
 from standard input. Exiting with non-zero status from this script prevent
 `git-p4 submit` from launching. Run `git-p4 submit --help` for details.
 
+post-indexchanged
+~~~~~~~~~~~~~~~~~
+
+This hook is invoked when the index is written in read-cache.c
+do_write_locked_index.
+
+The first parameter passed to the hook is the indicator for the
+working directory being updated.  "1" meaning working directory
+was updated or "0" when the working directory was not updated.
+
+The second parameter passed to the hook is the indicator for whether
+or not the index was updated and the skip-worktree bit could have
+changed.  "1" meaning skip-worktree bits could have been updated
+and "0" meaning they were not.
+
+Only one parameter should be set to "1" when the hook runs.  The hook
+running passing "1", "1" should not be possible.
+
 GIT
 ---
 Part of the linkgit:git[1] suite
-- 
2.20.1.windows.1