[3.0] ISO edit: Use sentence casing in headings

[bact]

To address issue

• https://github.com/spdx/spdx-spec/issues/239

[bact]

CI failed because the new heading value does not matched what spec-parser expected ("Property values" vs "Property Values"):

https://github.com/spdx/spec-parser/blob/3550116f10972d2398561b0d178ee7aca0e76e1f/spec_parser/loaders.py#L97-L98

[bact]

There is no need to change anything in the model files ("Profile Conformance", "Property Values", etc.). The generated section names come from templates, not the input.

I am not in favor of applying different rules. Having one thing that applied consistently makes things easier.

I see not harm of being consistent.

[bact]

It is more difficult to tell people that,

"when write for spdx-spec uses sentence casing, but when write for spdx-3-model uses title casing - unless spec-parser will failed"

than

"just use sentence casing everywhere".

[zvr]

No, we tell them:

• in text, in the spec repo, use sentence case
• in special formatted files, in the model repo, use one of the predefined headers

[goneall]

Moved to 3.1 milestone to close before next release

[kestewart]

This is a bit too late for the ISO submission. Let's discuss getting this consistence going forward for 3.1, unless ISO feedback points it out. More important right now to get it submitted.

[goneall]

@bact @zvr - can we close this and the related #1129 issues since we already submitted to ISO? If not, should we discuss on one of the tech calls?