docs(Rust.md): Add caveats from README

[TheJanzap]

The README mentions two caveats that are not currently mentioned in the more detailed Rust.md. I've added these to Rust.md

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 74.17%. Comparing base (b81fdbb) to head (406183e).
⚠️ Report is 4 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2684      +/-   ##
==========================================
+ Coverage   73.58%   74.17%   +0.58%     
==========================================
  Files          70       70              
  Lines       38220    39220    +1000     
==========================================
+ Hits        28125    29090     +965     
- Misses      10095    10130      +35     

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