docs: Fixed a broken link in the doc comments of session.rs

[takaiyuk]

Fixed a broken link.

Check Environment link in Type storing the session information, built from an Environment.

https://docs.rs/ort/1.15.4/ort/session/struct.Session.html

[codecov]

Codecov Report

All modified lines are covered by tests ✅

Comparison is base (ba9df19) 52.45% compared to head (852b73f) 51.88%.
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #95      +/-   ##
==========================================
- Coverage   52.45%   51.88%   -0.58%     
==========================================
  Files          13       13              
  Lines        1098     1089       -9     
==========================================
- Hits          576      565      -11     
- Misses        522      524       +2     

Files	Coverage Δ
src/execution_providers.rs	55.69% <ø> (-0.56%)	⬇️
src/session.rs	64.43% <ø> (-0.33%)	⬇️

... and 5 files with indirect coverage changes

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