Update patch_capabilities.pl help to be a little bit clearer

I certainly didn't read it well enough to notice I needed the third
parameter with template pkg files.

Reviewed-by: Jason Barron
(cherry picked from commit 36304a7)

bin/patch_capabilities.pl

@@ -51,8 +51,8 @@ ()
     print("specified for deployment in a .pkg file.\n");
     print("If no capabilities are given, the binaries will be given the\n");
     print("capabilities supported by self-signed certificates.\n");
-    print("\nUsage: patch_capabilities.pl pkg_filename [target-platform] [capability list]\n");
-    print("    If template .pkg file is given, next agrument must be 'target-platform'.\n");
+    print("\n *** NOTE: If *_template.pkg file is given, 'target-platform' is REQUIRED. ***\n");
+    print("\nUsage: patch_capabilities.pl pkg_filename <target-platform> [capability list]\n");
     print("\nE.g. patch_capabilities.pl myapp_template.pkg release-armv5 \"All -TCB\"\n");
     exit();
 }