📝 Updated test_containers README for MacOS and LTS SP1

Author: robmcdougall

rest-services/test_containers/ReadMe.md

@@ -13,3 +13,5 @@ different than the one in the steps above, then `AEM_IMAGE_NAME` may also need t
 The `ff_it_test_65.dockerfile` is provided for creating an integration test environment for AEM 6.5 (non-LTS).  This
 assumes that an AEM 6.5 non-LTS base container is available with FluentForms v0.0.3 installed.  It is useful to test that 
 v0.0.3 is still compatible with the latest AEM 6.5 service packs and with the client libraries running on later versions of Java.
+
+Note: On Macs, you can add `--platform linux/amd64` to the command to generate an x86_64 image since AEM only supports x86_64 Linux variants.