Add useful search snippets on sourcegraph.com

Created by: malomarrec

Snippets are designed to be small shortcuts to adding modifiers to a search query. They are designed to be additive.

Current behaviour

Snippets are "use cases" such as "popular npm packages". After I enter a search query, if I click on a snippet I'll most likely see no results, because my search query (eg. "print") will be concatenated with "repogroup:npm" which yields no results.

Proposed behaviour

Quick fix After searching for a term, I can discover useful search modifiers rapidly by using search snippets, eg:

• "show all matching repos": select:repo count:all
• "include forks": forks:yes
• "search within repo": repo:^github\.com/sourcegraph/sourcegraph$