Improve documentation test

What does this MR do?

This MR makes a couple of small changes:

• removes (https?:){0} from InternalLinkExtension Vale rule (which does nothing because of the zero regex quantifier, {0})
• replaces .+? ("any character one or more times, optional") with .* (any character zero or more times), which is logically equivalent and more common
• removes (- ){0} from VersionText.yml Vale rule
• fixes a bug (replaces [^\n`] with [^\n]) in VersionText.yml Vale rule, introduced in 39aad853
• fixes a broken link
• replaces master branch with main branch (style guide)

How to setup and validate locally

1. Run vale --minAlertLevel=error doc/
2. Check for ✔ 0 errors, 0 warnings and 0 suggestions in 1307 files.

Does this MR meet the acceptance criteria?

Conformity

• I have included changelog trailers, or none are needed. (Does this MR need a changelog?)
• I have added/updated documentation, or it's not needed. (Is documentation required?)
• I have properly separated EE content from FOSS, or this MR is FOSS only. (Where should EE code go?)
• I have added information for database reviewers in the MR description, or it's not needed. (Does this MR have database related changes?)
• I have self-reviewed this MR per code review guidelines.
• This MR does not harm performance, or I have asked a reviewer to help assess the performance impact. (Merge request performance guidelines)
• I have followed the style guides.
• This change is backwards compatible across updates, or this does not apply.