Don't use test_suite_mpi as an example

It just got renamed, and it's also not the most canonical example since it's
a somewhat deprecated interface. Make a different module the example.

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
diff --git a/tests/scripts/generate-afl-tests.sh b/tests/scripts/generate-afl-tests.sh
index 7c9f432..a640b56 100755
--- a/tests/scripts/generate-afl-tests.sh
+++ b/tests/scripts/generate-afl-tests.sh
@@ -6,7 +6,7 @@
 #
 # Usage: generate-afl-tests.sh <test data file path>
 #  <test data file path> - should be the path to one of the test suite files
-#                          such as 'test_suite_mpi.data'
+#                          such as 'test_suite_rsa.data'
 #
 # Copyright The Mbed TLS Contributors
 # SPDX-License-Identifier: Apache-2.0