Confusing (or wrong?) docs for hadrian user settings

Summary

hadrian/doc/user-settings.md says:

You can customise Hadrian in two ways:

• By selecting a flavour, flavour transformers and using key-value settings, either in the command line or by modifying the hadrian.settings file in the build directory.

But there is no such file as hadrian.settings in the whole build tree.

Proposed improvements or changes

If this file has been renamed or moved, the docs should be updated to reflect it. If the file is supposed to be generated or written by the user from scratch, then the docs should say so, and in particular should say where "the build directory is" (is that the project root or ./hadrian or what?).