Doc/Michelson: redirect operations on big_maps to interactive reference

Context

Answers this part of #4077:

• delete the parts about instructions from the static reference:
  • Operations on big_maps

The documentation about all the operations on big_map in the interactive reference contains that found in the static reference.
Note that the documentation of UPDATE is being fixed: michelson-reference!87 (merged).
The inclusion was checked manually by comparing the static and interactive documentations for each type and comparison instruction of the static reference.

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

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