Document how XR connection details work in v2

[jbw976]

What's Missing?

There's a bit of confusion, and out of date documentation, for how connection details work for XRs in v2.

Some of the problems are captured in crossplane/crossplane#6837 (comment).

TL;DR, we removed connection details from XRs in v2, but we don't have good documentation and guidance on how to handle that. Nic's suggestion in crossplane/crossplane#6440 is the only "doc" i know of:

I feel comfortable dropping this functionality (from core) for v2 XRs because in v2 you can recreate it using functions - just have your XR compose a secret with the XR's connection details in it.

We should perhaps consider surfacing this more clearly as a breaking change too, depending on the scope of impact once that is better assessed.

Related fixes:

• fix: fix connection details page so XRD and Composition keys match #1033
• Add guide for XR connection details in v2 #1034
• update v2 release notes with clear breaking changes note https://github.com/crossplane/crossplane/releases/tag/v2.0.0
• feat: modify default printer columns crossplane#5984
• update connection details blog post to point to new guide: https://blog.crossplane.io/faq-2-claim-connection-details/
• Update guides/content on XR connection details for v2 #1035
• feat: automatic connection details support for v2 XRs crossplane-contrib/function-patch-and-transform#278
• Update README and examples for v2 connection details behavior crossplane-contrib/function-go-templating#530
• Update README and examples for v2 connection details behavior crossplane-contrib/function-kcl#360
• chore: update run function proto comments for v2 connection details crossplane#6992
• chore: update run function proto comments for v2 connection details function-sdk-go#250
• chore: update run function proto comments for v2 connection details function-sdk-python#191