Broken documentation for filebeat/beater/PluginFactory

[richard-mauri]

When you click on the PluginFactory link https://godoc.org/github.com/elastic/beats/v7/filebeat/beater#PluginFactory it takes you to an error page

There is a breaking API change in filebeat/cmd/root.go where the RootCmd public variable is removed in the v7 module.
There is a FileBeat API that takes a PluginFactory and the doc is broken.

[LIAM1543]

I'm only seeing "Internal server error." on nearly every page.. Pretty major issue.