Expand e2e instructions.

@lavalamp 
insert:

```
# Flags can be combined, and their actions will take place in this order:
# -build, -push|-up|-pushup, -test|-tests=..., -down
# e.g.:
go run e2e.go -build -pushup -test -down

# -v (verbose) can be added if you want streaming output instead of only
# seeing the output of failed commands.

# -ctl can be used to quickly call kubectl against your e2e cluster. Useful for
# cleaning up after a failed test or viewing logs.
go run e2e.go -ctl='get events'
go run e2e.go -ctl='delete pod foobar'
```