fix(docs): Fix various broken links in docs

[agrski]

What this PR does / why we need it:
This PR fixes issues in the Core v2 docs from the models page to Rclone details regarding Docker and Kubernetes.

Which issue(s) this PR fixes:
Fixes #5045

Special notes for your reviewer:
The use of myst_heading_anchors fixes a number of other broken links due to the default for this being 2.

See these warnings from a local build:

docs/source/contents/metrics/usage.md:16: WARNING: 'myst' cross-reference target not found: 'extra-publish-urls' [myst.xref_missing]
docs/source/contents/metrics/usage.md:27: WARNING: 'myst' cross-reference target not found: 'metrics-levels' [myst.xref_missing]
docs/source/contents/metrics/usage.md:29: WARNING: 'myst' cross-reference target not found: 'list-of-metrics' [myst.xref_missing]
docs/source/contents/metrics/usage.md:78: WARNING: 'myst' cross-reference target not found: 'setting-options' [myst.xref_missing]

The usage metrics page has ### Extra publish URLs, i.e. an H3, which is not found with the H2 default.

[agrski]

@cliveseldon I think there are a couple of links which aren't just broken, but rather the content has fundamentally changed.

For example, see the link right at the end of this section for pipeline triggers.

This errors example is also only referenced, but seemingly never used:

$ rg 'error\.yaml' docs/source/
docs/source/contents/pipelines/index.md
190:```{literalinclude} ../../../../samples/pipelines/error.yaml

[agrski]

Linting issues seem to be wholly unrelated to this PR. Any way we can ignore @cliveseldon?

These seem to have only cropped up within the last few hours, maybe? Builds from 2 days ago didn't have this, but one from earlier today does.

For me locally, with Go 1.19.6 and golangci-lint 1.51.2, running make -C scheduler lint does not return any errors, just the warnings about deprecated linters.