README.md has wrong link for required patch for CLangFormat to work

The README file (https://code.qt.io/cgit/qt-creator/qt-creator.git/tree/README.md) states that in order to build/run ClangFormat plugin one needs to re-build llvm (clang) with a custom patch (as in https://codereview.qt-project.org/c/qt-creator/qt-creator/+/273375 )

However, the provided URL to the patch is incorrect. That patch is already merged upstream (to llvm-10 at the very least). The required patch is not yet merged. The one from this review: https://reviews.llvm.org/D53072

Can you please update the description with a correct patch URL?