rfc1: remove maintainer self-merge loophole

Problem: RFC 1 says maintainers may merge their own commits
after no response for 1-2 days, but this contradicts both
current practice and RFC 48 (governance).

Self-merging is a SHOULD NOT, "except in exceptional cases".

We could discuss valid examples here, but for now let's just
remove the contradictory example.

Author: garlick

spec_1.rst

@@ -154,7 +154,7 @@ Development Process
 
 -  To accept or reject a patch, a Maintainer SHALL use the Platform interface.
 
--  Maintainers SHOULD NOT merge their own patches except in exceptional cases, such as non-responsiveness from other Maintainers for an extended period (more than 1-2 days).
+-  Maintainers SHOULD NOT merge their own patches except in exceptional cases.
 
 -  Maintainers SHALL NOT make value judgments on correct patches.