efi_loader: add a README.iscsi describing booting via iSCSI

The appended README explains how U-Boot and iPXE can be used
to boot a diskless system from an iSCSI SAN.

The maintainer for README.efi and README.iscsi is set.

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
[agraf: s/Adress/Address/]
Signed-off-by: Alexander Graf <agraf@suse.de>
diff --git a/MAINTAINERS b/MAINTAINERS
index 0c7efde..0aecc18 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -289,6 +289,7 @@
 M:	Alexander Graf <agraf@suse.de>
 S:	Maintained
 T:	git git://github.com/agraf/u-boot.git
+F:	doc/README.iscsi
 F:	include/efi*
 F:	lib/efi*/
 F:	test/py/tests/test_efi*