Hypothesis search does not include page title

### Steps to reproduce
1. Use Hypothesis Chrome extension to add a page note to a page
2. Search Hypothesis for a keyword included in the title of the page you just annotated (https://hypothes.is/users/?q=)

### Expected behaviour
Hypothesis finds the page you just annotated

### Actual behaviour
No results

### Browser/system information
OS: Debian, kernel .10.19-1
Browser: Google Chrome 90.0.4430.93 (Official Build) (64-bit)

### Additional details
It seems Hypothesis does match the URL, why not also match the title?

Start by reproducing the search through the Hypothesis Chrome extension and the user search URL with a keyword from an annotated page title. Compare the existing URL matching with title matching, then verify that a title keyword returns the page note while unrelated keywords still return no result.

Written by the indexing model from the issue text.