SPDX: Add ISC SPDX-License-Identifier

Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>
Cc: Wolfgang Denk <wd@denx.de>
diff --git a/Licenses/README b/Licenses/README
index c6ff277..fe6dadc 100644
--- a/Licenses/README
+++ b/Licenses/README
@@ -66,3 +66,4 @@
 BSD 3-clause "New" or "Revised" License		BSD-3-Clause	Y		bsd-3-clause.txt	http://spdx.org/licenses/BSD-3-Clause#licenseText
 IBM PIBS (PowerPC Initialization and		IBM-pibs			ibm-pibs.txt
 	Boot Software) license
+ISC License					ISC		Y		isc.txt			https://spdx.org/licenses/ISC