Add additional sentences

Author: mkhorton

crystal_toolkit/apps/examples/tests/readme.md

@@ -1,5 +1,12 @@
 # End-to-end Testing
 
+The tests for this code are constructed as small example apps. Running a test might involve simply verifying the app starts
+correctly, checking console log output does not have errors, simulating user interaction, and taking screenshots of the
+app state to ensure that the app looks as expected.
+
+Ideally, each individual component should have at least one example app. The example apps are also used to demonstrate
+correct usage of these components.
+
 ## Dependencies
 
 The tests in this folder need the dependencies specified in `tests/requirements.txt`, in particular `dash[testing]` and `selenium`.
@@ -25,4 +32,4 @@ brew install --cask chromedriver
 brew install --cask google-chrome
 ```
 
-macOs may complain that it cannot verify the security of these executables in which case you can manually override and give permission in 'System Preferences > Security & Privacy'.
+macOS may complain that it cannot verify the security of these executables in which case you can manually override and give permission in 'System Preferences > Security & Privacy'.