This patch contains the following changes:

* Remove include directive for MAINTAINERS file, that does not exist
  anymore. Instead, add the COMMITTERS.rst file, which is the logical
  replacement for the MAINTAINERS file.

* Recursively include all requirements files instead of listing them one
  by one. This also fixes and issue where the cov-requirements files
  were not included in the source distribution.

* Simplify `recursive-include DIR *` to `graft DIR`. These two forms are
  functionally equivalent, but the latter is a bit easier to understand.