fix warning in docs generation

[robertchristensen]

Fixes warnings in docs generations:

1. Two links in docs in functions in the Curve trait were not correctly referenced, so I added references to the functions they were trying to reference.
2. Two links in portfolio.rs had redundant information when referencing other parts of the code causing errors in docs generation so they were removed.

After this I don't see any warning in docs generation when I build locally, and I the links go to the functions.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (13c37a0) 69.13% compared to head (217503f) 69.13%.
Report is 3 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #159   +/-   ##
=======================================
  Coverage   69.13%   69.13%           
=======================================
  Files         104      104           
  Lines        3690     3690           
=======================================
  Hits         2551     2551           
  Misses       1139     1139           

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[avhz]

Awesome, thank you very much !