[pyhumod] Use README.gentoo for installation notes.

Package-Manager: portage-2.1.11.31
Manifest-Sign-Key: C0174749
[maildirproc] Use README.gentoo for installation notes.

Package-Manager: portage-2.1.11.31
Manifest-Sign-Key: C0174749
[maildirproc-python2] Use README.gentoo for installation notes.

Package-Manager: portage-2.1.11.31
Manifest-Sign-Key: C0174749
Merge branch 'feat/readme_gentoo'

* feat/readme_gentoo:
  [maildirproc-python2] Use README.gentoo for installation notes.
  [maildirproc] Use README.gentoo for installation notes.
  [pyhumod] Use README.gentoo for installation notes.