hack/verify-generated-docs.sh: clarify error output

When the hack/verify-generated-docs.sh job fails because a generated
file was edited instead of the sigs.yaml file, it is less than clear
from the error message that the user still needs to manually commit the
generated docs in addition to changing the sigs.yaml and validating that
the docs do build.  A small additional bit of guidance is appended to
the existing hint in the test error output.

Signed-off-by: Tim Pepper <tpepper@vmware.com>

hack/verify-generated-docs.sh

@@ -54,7 +54,8 @@ if [[ ${mismatches} -gt "0" ]]; then
   fi
   echo "${mismatches} ${noun} detected."
   echo "Do not manually edit sig-list.md or README.md files inside the sig folders."
-  echo "Instead make your changes to sigs.yaml and then run \`make\`.";
+  echo "Instead make your changes to sigs.yaml, then run \`make\`, and then"
+  echo "commit your changes to sigs.yaml and any generated docs.";
   echo "${break}"
   exit 1;
 fi