Improve changeset copy for appsignal.rb file

These are suggestions from the review and my own improvements.

.changesets/add-config-appsignal-rb-file-support.md

@@ -5,7 +5,7 @@ type: add
 
 Add `config/appsignal.rb` config file support. When a `config/appsignal.rb` file is present in the app, the Ruby gem will automatically load it when `Appsignal.start` is called.
 
-The `config/appsignal.rb` config file is a replacement for the `config/appsignal.yml` config file. When both files are present, only the `config/appsignal.rb` config file is loaded.
+The `config/appsignal.rb` config file is a replacement for the `config/appsignal.yml` config file. When both files are present, only the `config/appsignal.rb` config file is loaded when the configuration file is automatically loaded by AppSignal  when the configuration file is automatically loaded by AppSignal.
 
 Example `config/appsignal.rb` config file:
 
@@ -16,4 +16,17 @@ Appsignal.configure do |config|
 end
 ```
 
-It is not possible to configure multiple environments in the `config/appsignal.rb` config file as it was possible in the YAML version.
+To configure different option values for environments in the `config/appsignal.rb` config file, use if-statements:
+
+```ruby
+# config/appsignal.rb
+Appsignal.configure do |config|
+  config.name = "My app name"
+  if config.env == "production"
+    config.ignore_actions << "My production action"
+  end
+  if config.env == "staging"
+    config.ignore_actions << "My staging action"
+  end
+end
+```