Better search handling to exclude unwanted crates

[ambaxter]

When searching through crates.io for "kubernetes" and ordered by "recent updates," you will see pages of "kcr_" prefixed crates. These are generated from the https://github.com/metio/kube-custom-resources-rs project.

These 406 crates are automatically updated and published every Sunday from this project. This pollution makes it impossible to properly search for new or interesting crates with the "kubernetes" keyword.

I'd like a "-" or similar symbol added to the search capabilities so that I can ignore these crates.