Generate code coverage and add icon to README.md Issue

[Cormwww]

I have finished the coverage report and added a badge to the read.me file after an embarrassing amount of time trying to figure out how to use rust.

[lyrakisk]

Hi, thank you for offering your help on this! Unfortunately, the current PR doesn't solve the problem at hand. I can give you some pointers:

• There is no need for a new rust.yml file, as the project already has ci.yml which runs the cargo tests
• At the moment, I see you hardcoded the coverage icon, so it will always display 35%, no matter what the real code coverage is. We don't want that. What we want, is to:
  • generate a code coverage report after running the tests
  • use this information to generate an icon that shows the real code coverage.

[Cormwww]

I think now the code should work and you only need to run a coverage test for the badge to work in the readme file.