Search Box May Not Be Searching The User Guide As Intended

[osscontributor]

At https://grails.org/search.html is the following:

You can search the Grails® website, the Grails documentation, and the Grails APIs with the Google Custom Search box below. Please type your search query and hit enter.

The search box is supposed to be searching the Grails docs but if I search for common terms like "controller" or "taglib" or "gsp", none of those yield any results from the user guide. It does find results in the Groovy documentation. I think that should be configured to search at least the user guide and the javadocs.