Investigate adding tests to documentation

[mike-solomon]

• We had tests added back to the documentation last year: Add test examples to docs again #74

It seems like that's not working. We need to investigate that and see what we can do to add tests back or link to tests or whatnot.

[timtebeek]

An example was posted in Slack:

• The documentation page does not contain an example: https://docs.openrewrite.org/recipes/java/addorupdateannotationattribute
• The example has been extracted and stored in https://github.com/openrewrite/rewrite/blob/f9d22950809aa07e25d3ee84628c233a8fa26cd8/rewrite-java-test/src/main/resources/META-INF/rewrite/examples.yml#L44-L74

Whereas for other recipes we're still seeing examples:

• https://docs.openrewrite.org/recipes/java/testing/assertj/staticimports

What I think is happening here is that the examples file should be in rewrite-java, not in rewrite-java-test.