Ability to check for normative text (BCP14 text)

[ajeanmahoney]

Check for the presence of the following boilerplate in the document:

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in
BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.

Check that one or more of the key words are used in the document (the RPC script that currently does this is findkeywords). If the key words are not used but the boilerplate is included, provide a warning that no key words are used but bcp14 boilerplate exists.

If key words are used, check that they are appropriately tagged. In RFCXML, the <bcp14> tag should be applied to each key word instance (the RPC script that current does this is checkbcp14); in kramdown-rfc, {::boilerplate bcp14-tagged} should exist in the file.

Allow the user to either step through instances of untagged key words and apply tags or to "Tag all" without the verification step. Note that keywords in sourcecode are not tagged and should not be included. The equivalent RPC script is simple-bcp-fix.pl.