Documentation: describe 'union' low-level merge driver

diff --git a/Documentation/git-update-ref.txt b/Documentation/git-update-ref.txt
index 9424feab320afcaa5a44bd2c2c6c86728bd8d004..f222616591f157beada3c5355ee0e56d68171761 100644 (file)
--- a/Documentation/git-update-ref.txt
+++ b/Documentation/git-update-ref.txt
@@ -7,7 +7,7 @@ git-update-ref - Update the object name stored in a ref safely
 
 SYNOPSIS
 --------
-'git-update-ref' [-m <reason>] (-d <ref> <oldvalue> | <ref> <newvalue> [<oldvalue>])
+'git-update-ref' [-m <reason>] (-d <ref> <oldvalue> | [--no-deref] <ref> <newvalue> [<oldvalue>])
 
 DESCRIPTION
 -----------
@@ -36,6 +36,9 @@ them and update them as a regular file (i.e. it will allow the
 filesystem to follow them, but will overwrite such a symlink to
 somewhere else with a regular filename).
 
+If --no-deref is given, <ref> itself is overwritten, rather than
+the result of following the symbolic pointers.
+
 In general, using
 
        git-update-ref HEAD "$head"