Doc/Michelson: redirect sapling operations to interactive reference

Context

Answers this part of #4077:

• delete the parts about instructions from the static reference:
  • Sapling operations

The documentation about sapling operations on the interactive reference is not up-to-date for SAPLING_VERIFY_UPDATE: the typing rule is incorrect michelson-reference!116 (merged).

Also note that the semantics rule in the static reference is explained in the description of SAPLING_EMPTY_STATE.

Manually testing the MR

make -C docs -j

And then open docs/_build/alpha/michelson.html in a web browser.

Or open the exposed artifacts Documentation - excluding old protocols below, and navigate to docs/_build/alpha/michelson.html.

Checklist

• Select suitable reviewers using the Reviewers field below.
• Select as Assignee the next person who should take action on that MR