Update development section in readme

Publishing v2 showed me that the guidance was generic and incorrect!

README.md

@@ -158,9 +158,13 @@ If you're using ActionMailer with Rails, [previews](https://guides.rubyonrails.o
 
 ## Development
 
-After checking out the repo, run `bin/setup` to install dependencies. Then, run `bundle exec rake spec` to run the tests. You can also run `bin/console` for an interactive prompt that will allow you to experiment.
+After checking out the repo, run `bin/setup` to install dependencies. Then, run
+`bin/rspec` to run the tests. You can also run `bin/console` for an interactive
+prompt that will allow you to experiment.
 
-To install this gem onto your local machine, run `bundle exec rake install`. To release a new version, update the version number in `version.rb`, and then run `bundle exec rake release`, which will create a git tag for the version, push git commits and tags, and push the `.gem` file to [rubygems.org](https://rubygems.org).
+To release a new version, update the version number in `version.rb`, and then
+tag the commit on main - the release will be built and published by the
+`publish.yml` GitHub action.
 
 ## Contributing