Classify normative tag markup-only changes

[Rafael Sene (rpsene)]

No description provided.

[Bill Traynor (wmat)]

Rafael Sene (@rpsene) is this still valid?

[Rafael Sene (rpsene)]

No, it is not. This one has been overtaken.

#244 improved tools/detect_tag_changes.py so markup-only edits to a normative
tag would not be reported as content changes. The script's only consumer was the
check-normative-tags workflow in riscv-isa-manual, and that went away in
riscv/riscv-isa-manual#3334 when James withdrew the original request in
riscv/riscv-isa-manual#2145. You then removed the script itself in #260, which is
the right call, and I confirmed there are no remaining references to it anywhere
in the riscv org.

Closing this. If we ever bring the check back, the markup-versus-content
classification and the two fixture files in this PR are the part worth reviving,
so the diff is worth a look before rewriting it from scratch.

Thanks for chasing it down.