Support CommonMark 0.31.2 specs

[rock3r]

Is your feature request related to a problem? Please describe. A new revision of the CommonMark spec was made available last month, 0.31.2. It looks like a minor spec revision, mostly concerning with updating links, but it does contain some tweaks.

Describe the solution you'd like Fully support the new changes to the spec.

Describe alternatives you've considered None available

Additional context https://spec.commonmark.org/0.31.2/