Streamline README (#261)

[manulera]

@BjornFJohansson you can have a look at the final readme here:

https://github.com/BjornFJohansson/pydna/blob/7b60609c04cc5bda93c53d3e56c35b3a8b50cd61/README.md

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 93.58%. Comparing base (245af37) to head (9e48b00).
Report is 12 commits behind head on dev_bjorn.

Additional details and impacted files

@@            Coverage Diff             @@
##           dev_bjorn     #278   +/-   ##
==========================================
  Coverage      93.57%   93.58%           
==========================================
  Files             40       40           
  Lines           3909     3913    +4     
  Branches         585      587    +2     
==========================================
+ Hits            3658     3662    +4     
  Misses           199      199           
  Partials          52       52           

Files with missing lines	Coverage Δ
src/pydna/amplify.py	98.67% <100.00%> (+0.01%)	⬆️
src/pydna/utils.py	93.17% <100.00%> (+0.05%)	⬆️