Add curve secp256K1

[cedelavergne-ledger]

Add new curve secp256K1, and update the documentation

Checklist

• App update process has been followed
• Target branch is develop
• Application version has been bumped

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 27.27%. Comparing base (d080e4f) to head (9f91786).

Additional details and impacted files

@@           Coverage Diff            @@
##           develop      #99   +/-   ##
========================================
  Coverage    27.27%   27.27%           
========================================
  Files            1        1           
  Lines          209      209           
========================================
  Hits            57       57           
  Misses         152      152           

Flag	Coverage Δ
unittests	27.27% <ø> (ø)

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