Fix inconsistent punctuation in rapi docs and opcodes

While reviewing the RAPI docs (for commit 003306f9), I realised that
the punctuation used in RAPI is inconsistent, especially with regards
to definition lists.

This patch changes all such lists to not have punctuation, except for
one case (the ecode descriptions, which have multiple
paragraphs). Furthermore, it fixes the few opcodes which had docs
ending with punctuation to not do so anymore.

Signed-off-by: Iustin Pop <iustin@google.com>
Reviewed-by: Michael Hanselmann <hansmi@google.com>