Update to Review Policy

[DRx3D]

Multiple updates included in this PR including:

• Updated new and revised model approval requirements.
• Incorporated @javagl changes from PR#5
• Moved model index files to the Models directory

Discussion of missing items in PR#5 has not yet been addressed and must be in the near future.

[javagl]

Regarding the last commit, just to keep track of this: The changes from #5 that are not included in the updated state of SubmittingModels.md are

• The link in There is an [experimental HTML application](../util/CreateJson.html) should start with a single dot . (otherwise, it leads to a 404 - but that may not be critical now, as long as this application is not "Live" on a website anyhow...)
• In the sentence The licensed assigned by the owner, it should probably be license (without d)
• The list of license shorthands at the bottom has to be reviewed.

The last point may not have addressed here, but should be sorted out either in an issue or a dedicated PR: We should be really, really careful to make sure that there is a place where the real SPDX license identifier can reliably be found, in a way that is machine-processable and unambiguous

(As in if (spdxLicenses.includes(thatValue)) { weKnowWhatToDoWithThat(); }...)

And in these identifiers ...

• CC0 is called CC0-1.0
• PD does not exist. I know, the concept of "public domain" is difficult, but CC0-1.0 is pretty clear from a legal point, and if some pettifogger is not satisfied with that, the model can be provided under a WTFPL license, dedicatedly issued for the person who does not understand that CC0-1.0 means exactly that...
• CC-BY does not exist. It might be CC-BY-1.0. And CC-BY International 4.0 is called CC-BY-4.0

[DRx3D]

@javagl : Please take a look at the revised version (direct link). I incorporated your changes and redid the descriptions of licenses at the end.

[javagl]

Looks fine for me. I guess that I'll close #5 soon then. Even if there are open questions, the PR itself has probably become obsolete.