Move `minimum_version` config to right place in README
Move `minimum_version` config to right place in README

This was incorrectly nested under "Local configuration" when it was
added in 32697c51.

trotzig/import-js,lencioni/import-js,trotzig/import-js,lencioni/import-js,Galooshi/import-js,lencioni/import-js,trotzig/import-js