Thanks, grandslambert And it helps even more to put the search term in quotes, e.g.:
site:www.ads-software.com/extend/plugins “improved plugin installation”
The problem of course is that it doesn’t work inside the WordPress Install Plugins page. Documenting the process of searching from within that page and installing a plugin, vs. searching the web and installing a plugin from a random website using an FTP program, is an order of magntitude different.