Update README

Author: n-rodriguez

README.md

@@ -31,30 +31,19 @@ Fork, fix, then send a Pull Request.
 
 To run the test suite locally against all supported frameworks:
 
-    % bundle install
-    % rake spec:all
+```sh
+bundle install
+bin/appraisal bundle install
+bin/appraisal rspec
+bin/appraisal rspec ./spec/requests/users_spec.rb
+```
 
 To target the test suite against one framework:
 
-    % rake spec:rails-4-2-stable
-
-You can find a list of supported spec tasks by running rake -T. You may also find it useful to run a specific test for a specific framework. To do so, you'll have to first make sure you have bundled everything for that configuration, then you can run the specific test:
-
-% BUNDLE_GEMFILE='gemfiles/rails-4-2-stable.gemfile' bundle install -j 4
-% BUNDLE_GEMFILE='gemfiles/rails-4-2-stable.gemfile' bundle exec rspec ./spec/requests/users_spec.rb
-
-### Rake and Bundler
-
-If you use a shell plugin (like oh-my-zsh:bundler) that auto-prefixes commands with `bundle exec` using the `rake` command will fail.
-
-Get the original command with `type -a rake`:
-
-    % type -a rake
-    rake is an alias for bundled_rake
-    rake is /Users/username/.rubies/ruby-2.2.3/bin/rake
-    rake is /usr/bin/rake
-
-In this situation `/Users/username/.rubies/ruby-2.2.3/bin/rake` is the command you should use.
+```sh
+bin/appraisal rails_8.1 rspec
+bin/appraisal rails_8.1 rspec ./spec/requests/users_spec.rb
+```
 
 ## License