Incorporate RFC2119 styling

[fantasai]

Incorporate RFC2119 styling

[fantasai]

See also https://lists.w3.org/Archives/Public/spec-prod/2023AprJun/0016.html which asks whether this convention should be

• optional or required
• altered in some way to improve screenreader compatibility

[fantasai]

(If we want to make it required, we should probably make sure ReSpec and Bikeshed can auto-generate the requisite markup.)

[tabatkins]

Yeah that markup is awkward as all hell to write out manually every single time. If we want to actually make this required, I'd probably have Bikeshed, like, autotransform 2119may into the markup, and then flag every normative use of 2119 language that isn't marked up.

[tabatkins]

But I'm happy to just not do it, and remove it from the Manual of Style too. CSS has never marked up its 2119 language in this way. (It also uses alternative wording in several places anyway, as noted in our Conformance sections, so if someone is depending on the literal word "MUST" or whatever to stand out and be noticeable, they'll miss most of the normative requirements already.

[fantasai]

Previous discussion, fwiw: #126