Adds documentation for the VMs bytecode

[Lichtso]

Put together from various pieces that @riptl @CantelopePeel and myself worked on 8 months ago:
https://github.com/firedancer-io/specs-old/blob/main/docs/protocol/sealevel/sbf/isa.md
https://github.com/firedancer-io/solana-improvement-documents/blob/sbpf-v2-spec/proposals/9999-sbpf-v2.md

Additionally wrote about the verifier and ISA version differences.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 89.43%. Comparing base (c478374) to head (7a6e742).
Report is 4 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #579      +/-   ##
==========================================
+ Coverage   89.41%   89.43%   +0.01%     
==========================================
  Files          23       23              
  Lines        9998     9993       -5     
==========================================
- Hits         8940     8937       -3     
+ Misses       1058     1056       -2     

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