Fix links to appropriate versions of docs, in preparation for redirec…

[stevepiercy]

…ting docs.plone.org to 6.docs.plone.org

• Fix a few other typos

[mister-roboto]

@stevepiercy thanks for creating this Pull Request and helping to improve Plone!

TL;DR: Finish pushing changes, pass all other checks, then paste a comment:

@jenkins-plone-org please run jobs

To ensure that these changes do not break other parts of Plone, the Plone test suite matrix needs to pass, but it takes 30-60 min. Other CI checks are usually much faster and the Plone Jenkins resources are limited, so when done pushing changes and all other checks pass either start all Jenkins PR jobs yourself, or simply add the comment above in this PR to start all the jobs automatically.

Happy hacking!

[stevepiercy]

Refs: https://github.com/plone/documentation/pull/1404

[stevepiercy]

I'm not sure how to fix the build failure, but here's the error message:

linkcheck: failed with mkdir is not allowed, use allowlist_externals to allow it

It works fine locally. ¯\_(ツ)_/¯

[stevepiercy]

I'm in favor of using the latest tox in CI. Should I do that in this PR or a separate one?

[mauritsvanrees]

I'm in favor of using the latest tox in CI. Should I do that in this PR or a separate one?

I don't mind. Your choice. I guess it fails on master as well already.

[stevepiercy]

This was fairly straightforward. There was a renaming of a configuration option in tox. Fix pushed, now waiting to see whether I got all the issues in GHA.

[stevepiercy]

Another tox 4 error:

ValueError: conflicting factors py37, 5.2 in py37-plone-5.2
  py[37](https://github.com/plone/plone.api/actions/runs/3792986432/jobs/6449673822#step:6:38)-plone-5.2: FAIL code 2 (0.00 seconds)
  evaluation failed :( (0.54 seconds)

I looked at the matrix in env_list, and noticed that the Pythons had no ., but the Plones did. I also noticed an extra -. It seemed that tox interpreted plone-5.2 as Python 5.2, which conflicted with Python 3.7. I removed those characters, and that seemed to resolve the matter locally. Let's see what GHA says.

[stevepiercy]

See also this excellent guide Breaking changes in tox 4. h/t @jugmac00

[stevepiercy]

@jenkins-plone-org please run jobs

[stevepiercy]

@mauritsvanrees all green on GHA. It can be clumsy to combine two things in a single PR and news item. Please let me know if you would like me to split them apart, and I can do so.

[mauritsvanrees]

Thanks!