https://coveord.atlassian.net/browse/DOC-18329

Two changes meant to improve the ranking score of typedoc pages, which is currently quite poor.

1. Change @coveo/headless to Coveo Headless in the title. This way, the Coveo index can match Headless with queries. It also more closely matches the rest of the site.
2. Split the function/object name from reference titles and append reference (e.g., buildAttachedResults becomes build attached results reference). Then, put that into a new meta tag I'll use for title indexing later, making it free text searchable. The rationale is that this way, we can return relevant reference pages when people query functions/object names non concatenated (e.g., build attached results headless reference). Here's what the tag looks like: