Feature suggestions now handled by GitHub issues
Since around 2012 Caniuse has been accepting suggestions for support tables to add to the site via Google Moderator. As Google has recently announced that the Moderator service will be shut down, all suggestions with 3+ votes have now been imported as GitHub issues.
While GitHub lacks a direct way of voting issues up or down, a system has been set up where anyone can vote for an issue with a "+1" comment. These votes are then tallied and the resulting list in order of votes is generated here.