update documentation regarding go 1.20 coverage tools

[mlctrez]

This issue to get your thoughts on a documentation update.
I think it would be a good add, but understand if it seems out of scope for this project's readme.

The code coverage tools introduced in go 1.20 produce multiple coverage data files in binary format, one of the drivers for #49

Using -test.coverprofie still works after #49 and produces the single coverage output file.

I'd like to submit a PR to add instructions (at a high level) that read:

• When generating coverage with go 1.20 and later:
  • Prefer the -test.gocoverdir option instead of -test.coverprofile for coverage generation.
  • Having less data across the http fs api calls is the primary benefit.
  • Post process the coverage data files using the go covdata tool.
  • As in go tool covdata -i <gocoverdir> -o coverage.out
  • A additional benefit is that wasm and nonwasm coverage runs can be merged with this command.

Thanks, Matt

[agnivade]

Makes sense. Please feel free to go ahead. Thanks!

[mlctrez]

Here you go: https://github.com/agnivade/wasmbrowsertest/pull/52

Link to readme in my branch.

[agnivade]

Closing as this is resolved now.