RelNotes-1.5.4: describe recent updates

Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/.mailmap b/.mailmap
index 5529b19..3b2ce57 100644
--- a/.mailmap
+++ b/.mailmap
@@ -37,6 +37,7 @@
 Santi Béjar <sbejar@gmail.com>
 Sean Estabrooks <seanlkml@sympatico.ca>
 Shawn O. Pearce <spearce@spearce.org>
+Steven Grimm <koreth@midwinter.com>
 Theodore Ts'o <tytso@mit.edu>
 Tony Luck <tony.luck@intel.com>
 Uwe Kleine-König <Uwe_Zeisberger@digi.com>