Add readme giving commands, expectations, actual and (small) triage.

hamcrest-to-assertj/README.md

@@ -0,0 +1,13 @@
+Meant to show an issue with 'AddDependency' when used on modified LST.
+
+```sh
+mvn org.openrewrite.maven:rewrite-maven-plugin:5.39.0:run \
+    -Drewrite.recipeArtifactCoordinates=org.openrewrite.recipe:rewrite-testing-frameworks:2.16.0 \
+    -Drewrite.activeRecipes=org.openrewrite.java.testing.hamcrest.MigrateHamcrestToAssertJ \
+    -Drewrite.exportDatatables=true
+```
+
+After this, I expect `App.java` should be changed and `assertj` dependency
+should be added to the pom.  However, only `App.java` is changed and code no
+longer compiles.  Debugging suggests a condition related to `onlyIfUsing` in
+`AddDependency` is not seeing the modified LST.