Documentation for requirement overriding is confusing

[samuel-emrys]

Overriding Requirements for conanfile.txt consumers indicates the override keyword can be provided:

You can use environment variable CONAN_ERROR_ON_OVERRIDE to raise an error for every overriden requirement not marked explicitly with the override keyword.

This currently only applies to conanfile.py files which can override in the following way:

def requirements(self):
    self.requires("zlib/1.2@drl/testing", private=True, override=True)

Should the documentation be updated to be explicit about the fact that the override keyword can't currently be provided in conanfile.txt?

I think this would also be a useful feature to have for conanfile.txt.