Documentation for strip_include_prefix references 'third_party' policy.

### Description of the bug:

https://bazel.build/reference/be/c-cpp#cc_library.strip_include_prefix

Docs mention "This attribute is only legal under third_party." which doesn't make sense for bazel.

### Which category does this issue belong to?

Documentation

### What's the simplest, easiest way to reproduce this bug? Please provide a minimal example if possible.

_No response_

### Which operating system are you running Bazel on?

_No response_

### What is the output of `bazel info release`?

_No response_

### If `bazel info release` returns `development version` or `(@non-git)`, tell us how you built Bazel.

_No response_

### What's the output of `git remote get-url origin; git rev-parse HEAD` ?

_No response_

### If this is a regression, please try to identify the Bazel commit where the bug was introduced with bazelisk --bisect.

_No response_

### Have you found anything relevant by searching the web?

_No response_

### Any other information, logs, or outputs that you want to share?

_No response_

Start with the linked strip_include_prefix reference at bazel.build/reference/be/c-cpp and locate the source that generates this attribute's documentation. Check the wording around the third_party policy, then verify the rendered reference no longer contains the incorrect Bazel-specific reference.

Written by the indexing model from the issue text.