[clang-tools-extra] Update clang tidy Contributing guide (PR #106672)

[Richard Thomson via cfe-commits]

LegalizeAdulthood wrote:

> Alternatively, pressing the tab key after a previous matcher's open parentheses would also

Did you try this on Windows?  Because in my experience all these TAB-complete actions depend on GNU readline which doesn't work on Windows.

https://github.com/llvm/llvm-project/pull/106672