Update README to reflect current best practices in creating and running tests

[vearutop]

Related to #472.

🤔 What's changed?

This PR updates README to

• prioritize go test usage over CLI godog as it grants better flexibility and familiarity for Go developers,
• use context.Context in step examples for better concurrency readiness.

⚡️ What's your motivation?

Running tests with CLI godog has limitations (#154) and is sometimes a bit obscure due to doing "magic" under the hood, using regular Go tests is (in my opinion) a better approach in general, so I think we should update documentation to encourage more go test usage.

🏷️ What kind of change is this?

• 🏦 Refactoring/debt/DX (improvement to code design, tooling, documentation etc. without changing behaviour)

♻️ Anything particular you want feedback on?

📋 Checklist:

• I agree to respect and uphold the Cucumber Community Code of Conduct
• I've changed the behaviour of the code
  • I have added/updated tests to cover my changes.
• My change requires a change to the documentation.
  • I have updated the documentation accordingly.
• Users should know about my change
  • I have added an entry to the "Unreleased" section of the CHANGELOG, linking to this pull request.

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This text was originally generated from a template, then edited by hand. You can modify the template here.

[codecov]

Codecov Report

Merging #477 (44d44b8) into main (d52a4d3) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             main     #477   +/-   ##
=======================================
  Coverage   81.42%   81.42%           
=======================================
  Files          27       27           
  Lines        2197     2197           
=======================================
  Hits         1789     1789           
  Misses        312      312           
  Partials       96       96           

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[mattwynne]

Looks good to me!

[mattwynne]