Better handling for the materialized view

By default, Tyra looks for a materialized view called `results.ranked_table`. Tyra shows many options in the dropdown box (e.g. top 100, top 10%), but it can only display results in that view. For example, if the materialized view only includes results for the top 5%, the top 100 option won't work.

- Tyra should populate the dropdown box with the options in `results.ranked_table`. That avoids giving the false impression that Tyra has more results than it does, and it also enables Tyra to handle non-standard results (such as precision on the top 1, which we rarely do)
- The documentation note that the materialized view needs to be updated if the user wants to see more recent results. In many deployments, we're making predictions and updating the evaluations every night. The documentation could note that a cron job would handle this well.

Start by locating where Tyra reads results.ranked_table and populates the dropdown, then inspect the documentation covering materialized-view updates. Done means the dropdown reflects the available results, non-standard options work, and the documentation explains refreshing the view and using a cron job.

Written by the indexing model from the issue text.