Fix propagation docs (#526)

* Fix typo - wrong example for "stopping propagation" section

* Move `lib.rs` in guide back to `src`

* Make sure tests get run when guide is updated (there's examples in the guide to check for compilation errors)

.github/workflows/main.yml

@@ -7,6 +7,7 @@ on:
     paths:
       - packages/**
       - examples/**
+      - docs/guide/**
       - src/**
       - .github/**
       - lib.rs