Search result ranking improvements

[mhilbrunner]

What's the problem this feature will solve?

Currently, the search results are ranked suboptimally in some ways.

• Exact matches, all terms being in the exact order (as opposed to matching only parts, or in different term order) seem to not be valued enough.
• Titles and document file names seem to count too little. These are the results for searching "audio" in Godot's documentation, note how "Documentation changelog" is ranked above a page titled "Audio buses":

https://github.com/readthedocs/readthedocs.org/issues/8670 would go a long way in helping with some of the cases we discovered, but the above should (hopefully) be fairly general improvements.

[stsewd]

Exact matches, all terms being in the exact order (as opposed to matching only parts, or in different term order) seem to not be valued enough.

Do you have a search example for this case?

Titles and document file names seem to count too little.

These are the boost we set for page title and section titles

https://github.com/readthedocs/readthedocs.org/blob/7198d3d3d628df8873d26b203db54f4c688e52dd/readthedocs/search/faceted_search.py#L271-L272

We can try boosting the page title with 2 as well.