Unwind an overly-aggressive backtick replacement from f9dc90b0 (make
link usage consistent across the specification, 2017-02-09, #687).
Signed-off-by: W. Trevor King <wking@tremily.us>
In all of these cases we want to use the RFC 2119 semantics.
Generated with:
$ sed -i 's/optional/OPTIONAL/g' config*.md
Signed-off-by: W. Trevor King <wking@tremily.us>