[FABG-793] Add note about libtool requirement

Change-Id: Icd5f3f6cca7308ffbf1d4cf41852d07df64c1ecc
Signed-off-by: Nye Liu <nye@blockdaemon.com>

Author: nyetwurk

README.md

@@ -84,6 +84,7 @@ You need:
 - Docker
 - Docker Compose
 - Git
+- libtool
 
 ### Gerrit Git repository
 
@@ -186,4 +187,4 @@ make dockerenv-latest-up
 Hyperledger Fabric SDK Go software is licensed under the [Apache License Version 2.0](LICENSE).
 
 ---
-This document is licensed under a <a rel="license" href="http://creativecommons.org/licenses/by/4.0/">Creative Commons Attribution 4.0 International License</a>.
+This document is licensed under a <a rel="license" href="http://creativecommons.org/licenses/by/4.0/">Creative Commons Attribution 4.0 International License</a>.