feat(fwu): update the URL links for the FWU specification

Update the links for accessing the FWU Multi Bank update specification
to point to the latest revision of the specification.

Change-Id: I25f35556a94ca81ca0a7463aebfcbc2d84595e8f
Signed-off-by: Sughosh Ganu <sughosh.ganu@linaro.org>
diff --git a/include/drivers/fwu/fwu_metadata.h b/include/drivers/fwu/fwu_metadata.h
index 2e88de5..7ff1176 100644
--- a/include/drivers/fwu/fwu_metadata.h
+++ b/include/drivers/fwu/fwu_metadata.h
@@ -4,7 +4,7 @@
  * SPDX-License-Identifier: BSD-3-Clause
  *
  * FWU metadata information as per the specification section 4.1:
- * https://developer.arm.com/documentation/den0118/a/
+ * https://developer.arm.com/documentation/den0118/latest/
  *
  */