Add Ecosystem Considerations/extension points annex

[GarethCOliver]

Throughout the text we have a lot of things we are deferring to the ecosystem. It would be good to have a section/annex about this, perhaps with example sets of choices (e.g. for how something like ISO mdl or EU could fit into this, as well as considerations when making these choices for ecosystems that are looking to achieve certain properties when making requirements around the use of HAIP).

[Sakurann]

wg discussion:

• generic support to add such text. this would help a lot of ecosystems. would like to be as specific as possible regarding the extension points that are left open.