Some extensions are ratified at least on the ISA specification version
20240411. This commit moves such extensions.
This commit also changes that:
1. Lower indentation of "Zk*" and "Zbk*" extensions to avoid extension
groups from being misleading inside this section.
2. Raise indentation of "Zfhmin" and "Zhinxmin" extensions to show that
they are a strict subset of "Zfh" and "Zhinx" (respectively).
3. Clarify that "s" is not an extension but a feature notifying
the existence of the supervisor-level ISA.
4. Clarify that "h" is not just an existence of the hypervisor-level ISA
but is also an extension name ("H").
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