fix(doc): clarify variable subkinds and aliases edge (#3979)
fix(doc): clarify variable subkinds and aliases edge (#3979)

* We weren't listing or testing variable subkinds for Java.
* Notation used in property-related edges suggested that
  `property` nodes were called `variable/property` instead.
  I don't believe this was the intention.
* We expect to see aliases used for imports.
kythe/kythe,kythe/kythe,kythe/kythe,kythe/kythe,kythe/kythe,kythe/kythe,kythe/kythe,kythe/kythe,kythe/kythe,kythe/kythe,kythe/kythe