[clang-tools-extra] [clang-tidy] Fix false positives in `bugprone-crtp-constructor-accessibility` check (PR #132543)

[Baranov Victor via cfe-commits]

vbvictor wrote:

> maybe we should mention it in check's doc also.

Added mention of this behavior in docs.


https://github.com/llvm/llvm-project/pull/132543