[clang-tools-extra] [clang-tools-extra] Fix typos in Modularize.rst (PR #99256)

[Vlad Serebrennikov via cfe-commits]

Endilll wrote:

We don't have to wait for Linux CI to finish to merge this, but private e-mail is an issue.

https://github.com/llvm/llvm-project/pull/99256