Had you read the linked release notes, you wouldn't have had to poke around to find that out: it's not some hidden thing. The second paragraph starts off with:

Had you read the linked release notes, you wouldn't have had to poke around to find that out: it's not some hidden thing. The second paragraph starts off with: As of Go 1.13, the go command by default downloads and authenticates modules using the Go module mirror and Go checksum database run by Google.