Add direct links to Python and C APIs from README

[hyanwong]

I use these a fair bit

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (77faade) 89.69% compared to head (664f574) 89.69%.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2887   +/-   ##
=======================================
  Coverage   89.69%   89.69%           
=======================================
  Files          30       30           
  Lines       30159    30159           
  Branches     5860     5860           
=======================================
  Hits        27052    27052           
  Misses       1778     1778           
  Partials     1329     1329           

Flag	Coverage Δ
c-tests	86.09% <ø> (ø)
lwt-tests	80.78% <ø> (ø)
python-c-tests	67.89% <ø> (ø)
python-tests	98.92% <ø> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

---

Continue to review full report in Codecov by Sentry.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 77faade...664f574. Read the comment docs.