Clarify OBI support, compatibility, and limitations docs

[MrAlias]

Updates the OBI docs under content/en/docs/zero-code/obi to make support, compatibility, and limitations clearer and more user-focused.

Follow-up to open-telemetry/opentelemetry-ebpf-instrumentation#1757 and open-telemetry/opentelemetry-ebpf-instrumentation#1760 which clarify OBI supported things.

This change:

• removes distro-version support claims from the OBI landing page and replaces them with a narrower, requirements-based compatibility summary
• separates support scope from limitations so the landing page is easier to scan and less repetitive
• moves detailed instrumentation compatibility information into the feature and instrumentation docs that already own that content
• adds explicit compatibility details for distributed tracing, protocol and library instrumentation, and GPU instrumentation
• cleans up links and section structure affected by the landing page rewrite

Docs changes

• updates content/en/docs/zero-code/obi/_index.md
  • merges the old Requirements content into Compatibility
  • keeps the landing page focused on platform requirements, published artifacts, support boundaries, and links to detailed support docs
  • narrows Limitations to actual observability and behavior constraints
• updates content/en/docs/zero-code/obi/distributed-traces.md
  • adds a compatibility section for context propagation support across supported runtimes and environments
• updates content/en/docs/zero-code/obi/configure/export-data.md
  • adds a top-level instrumentation compatibility section
  • documents supported protocol versions, runtime and server requirements, Go library compatibility, and GPU instrumentation compatibility
• updates content/en/docs/zero-code/obi/configure/collector-receiver.md
  • removes a weak link to the OBI landing page for the “minimal overhead” statement after the Requirements section was removed

Notes

• this change is intended to align the public docs with the current OBI support matrix without overstating support
• detailed feature caveats remain in the feature-specific pages rather than on the top-level OBI landing page

---

• I have read and followed the Contributing docs, especially the "First-time contributing?" section.
• This PR has content that I did not fully write myself.
  • I used AI and I have read and followed the Generative AI Contribution Policy.
• I have the experience and knowledge necessary to understand, review, and validate all content in this PR.¹

Footnotes

1. Yes, I can answer maintainer questions about the content of this PR, without using AI. ↩

[Copilot]

Pull request overview

This PR refines the OpenTelemetry eBPF Instrumentation (OBI) documentation to present support scope, compatibility requirements, and limitations more clearly, moving detailed compatibility specifics into the relevant feature/configuration pages.

Changes:

• Rewrites the OBI landing page to use requirements-based compatibility (instead of distro lists) and to separate support scope from limitations.
• Adds explicit compatibility matrices/details for distributed tracing context propagation and for protocol/library/GPU instrumentation.
• Cleans up wording/links impacted by the landing page restructure (including removing a now-weak cross-link in Collector receiver docs).

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 3 comments.

File	Description
content/en/docs/zero-code/obi/_index.md	Reworks landing page structure; adds requirement-based compatibility and clearer limitations with links to detailed pages.
content/en/docs/zero-code/obi/distributed-traces.md	Adds a compatibility section/table for distributed tracing and clarifies network-level gRPC/HTTP2 limitations.
content/en/docs/zero-code/obi/configure/export-data.md	Adds instrumentation compatibility sections covering protocols, runtime constraints, Go library support, and GPU/CUDA instrumentation.
content/en/docs/zero-code/obi/configure/collector-receiver.md	Removes a weakened link reference after the landing page restructure; keeps the performance note as plain text.

[theletterf]

@open-telemetry/ebpf-instrumentation-approvers Please have a look, thanks!