chore: apply code review suggestions, qol changes

[PaddseL]

Introduced changes:

• Added missing certificate type examples
• Added link to Industry Core: Basics reference in 4.1 NORMATIVE REFERENCES
• Reintroduced Certificate Available notification
• Fixed formatting of JSON examples
• Fixed spelling of certificate type in examples
• Fixed context references in openAPI yaml example
• Removed unused schemas from openAPI yaml example
• Fixed BpnLocation pattern in openAPI yaml example
• Removed relatedMessageId attribute from the example payloads because it is optional
• Adjusted Header in the openAPI yaml example to reuse the message header aspect model
• Fixed formatting of openAPI yaml example
• Reverted from Feedback notifications back to Status notifications to avoid introducing breaking changes
• Reverted dct subject renaming for the CCMAPI asset to avoid introducing breaking changes
• Formatting and QoL changes
• Removed the sentence This request can be sent by the Certificate Consumer continuously, for updates on the request state on Certificate Provider side. as discussed in the meeting on 12.11.