Refresh Kotlin example

[plaird]

I added a kotlin example a couple of years ago, in a branch, in this issue: #84

It needs a refresh. I had forgotten about it.

DoD:

• Refresh the branch with the latest from rules_spring, and a more recent version of rules_kotlin
• Add a note to the make_release.sh script to remind the operator (me!) of the kotlin branch, and the need to update it

Thanks for reporting @codemeariver1