To emphasize the happy path for updating Geo nodes, put the version
specific steps in a separate document and cross-link them for
discoverability.

Closes https://gitlab.com/gitlab-org/gitlab-ee/issues/11881

Clean up issues that may cause the docs-lint
test to fail, such as trailing whitespace, no
EOF newline, blockquotes, etc

Menu entries in global navigation will be updated to match.

Previously, we used brackets to denote the tier badges,
but this made Kramdown, the docs site Markdown renderer,
show many warnings when building the site. This is now
fixed by using parentheses instead of square brackets.

This was caused by [PREMIUM] looking like a link to
Kramdown, which couldn't find a URL there.

See:
- https://gitlab.com/gitlab-com/gitlab-docs/merge_requests/484
- https://gitlab.com/gitlab-org/gitlab-ce/issues/63800

Spacing following lists should be 2 spaces, and 3 for numbered lists