fix(guidelines): remove consumer-facing rules that have been included in API Portal

[BirgitBader]

Changelog:

Removal

The following rules have been removed as they contained consumer-facing content. This content has been included in the API Portal in the REST API sections "Status codes", "Headers" "Preview", and "Deprecation" respectively.

• MUST NOT rely on API components marked as preview
• MUST NOT not start using deprecated APIs
• MUST accept undocumented status codes
• MUST follow redirection
• SHOULD honor available ETag header on subsequent modifications

[BirgitBader]

For your review @plemech23 🙂

[cgebken]

Almost perfect ;) Furthermore, I was wondering if we should add the rule numbers in the changelog? Usually the number is pretty prominent and if people only noted the number but not the rule name, they might still find the information that it was removed @BirgitBader ?

[BirgitBader]

Almost perfect ;) Furthermore, I was wondering if we should add the rule numbers in the changelog? Usually the number is pretty prominent and if people only noted the number but not the rule name, they might still find the information that it was removed @BirgitBader ?

I remember that we discussed this already, when we crafted the PR template for the guidelines. And we decided against it.
We already had a removal on 2023-06-23 and it worked well.