Separate list of Submitters from that of Contributors

[ghobona]

This issue came up during the OGC API - Features SWG telecon on 2020-09-14.

The Standards template currently only lists Submitters.

In some cases, a contributor may not wish to be listed as a submitter because submitting may imply that the organisation endorses the standard.

Therefore, there was a request to have a separate list for Contributors.

[ogcscotts]

See Issue #24 - the next template update will include a formal place for contributors. Contributors have been included in some Standards documents in the past.