Add clarification on the meaning of the presence or otherwise of the container Flow property, previously only stated in AppNote0006.

Author: j616

api/schemas/flow-core.json

@@ -85,7 +85,7 @@
         },
         "container":
         {
-            "description": "The container MIME type for Flow Segments. Note that the `type` component of the container MIME type (i.e. the component before the `/`) may be different to the `type` component of the codec MIME type. e.g. An audio Flow may have `audio/aac` coded content may be wrapped in a `video/mp2t` container. Where multiple types exist for a subtype (e.g. `video/mp4`, `audio/mp4`, `application/mp4`), the closest MIME type to the Flow `format` should be used (e.g. `audio/mp4` for a Flow `format` of `urn:x-nmos:format:audio`). Mime types from the [IANA registry](https://www.iana.org/assignments/media-types/media-types.xhtml) should be preferred. Where multiple MIME types are possible, the most common should be preferred. Where this is insufficient, the maintainers of the TAMS repository may create an application note advising which MIME type to use.",
+            "description": "The container MIME type for Flow Segments. Note that the `type` component of the container MIME type (i.e. the component before the `/`) may be different to the `type` component of the codec MIME type. e.g. An audio Flow may have `audio/aac` coded content may be wrapped in a `video/mp2t` container. Where multiple types exist for a subtype (e.g. `video/mp4`, `audio/mp4`, `application/mp4`), the closest MIME type to the Flow `format` should be used (e.g. `audio/mp4` for a Flow `format` of `urn:x-nmos:format:audio`). Mime types from the [IANA registry](https://www.iana.org/assignments/media-types/media-types.xhtml) should be preferred. Where multiple MIME types are possible, the most common should be preferred. Where this is insufficient, the maintainers of the TAMS repository may create an application note advising which MIME type to use. Where the Flow does not reference any Media Object(s) directly (e.g. an empty Multi Flow that serves only to collect related mono-essence Flows that do reference Media Objects), this property MUST NOT be set.",
             "$ref": "mime-type.json"
         },
         "avg_bit_rate":