Expand the RFC acronym at least once (#69)

* Expand the RFC acronym at least once

While it is probably know to most it should also be documented what we expand RFC to.

* Capitalize "RFC"

Co-authored-by: zimbatm <zimbatm@zimbatm.com>

Co-authored-by: Eelco Dolstra <edolstra@gmail.com>
Co-authored-by: zimbatm <zimbatm@zimbatm.com>

README.md

@@ -1,4 +1,4 @@
-# Nix RFCs
+# Nix RFCs (Request For Comments)
 
 Many changes, including bug fixes and documentation improvements can be
 implemented and reviewed via the normal GitHub pull request workflow.