golang-tools: add late recording for June, schedule September

And also swap Paul for myself in the instructions below.

Change-Id: I310c3aa4cf67353e01d0304e8d755d1a7618b95d
Reviewed-on: https://go-review.googlesource.com/c/wiki/+/602636
Reviewed-by: Robert Findley <rfindley@google.com>