"?" should display keyboard shortcuts

[benjaminclauss]

I would love to learn all the possible shortcuts so I can use the extension effectively. I was able to find them through this article. Similar to Gerrit and other tools, I think it would be great if the "?" key would open a popup with all the possible shortcuts to use.

[infokiller]

Thanks for proposing this feature, I agree it will be good to have it, though I likely won't have time to do it myself in the near future. You can see a more up to date list of keyboard shortcuts here: https://github.com/infokiller/web-search-navigator#keybindings