doc/git-mailrc: add Stefan Roese to the kirkwood alias

Stefan is listed as a kirkwood maintainer since commit f822d8578ba3
(MAINTAINERS: Update Marvell custodianship).

Signed-off-by: Baruch Siach <baruch@tkos.co.il>
Signed-off-by: Stefan Roese <sr@denx.de>

doc/git-mailrc

@@ -56,7 +56,7 @@ alias arm            uboot, aaribaud, trini
 alias at91           uboot, abiessmann
 alias davinci        ti
 alias imx            uboot, sbabic
-alias kirkwood       uboot, prafulla, luka
+alias kirkwood       uboot, prafulla, luka, stroese
 alias omap           ti
 alias pxa            uboot, marex
 alias rmobile        uboot, iwamatsu