WORKSPACE code for 0.39.1 release is not present on the github release description

Is it expected to have the `WORKSPACE` snippet for all of the releases present? Having the snippet with sha256 would be useful to build script updating local repos. I see that most of the release do have them, though.

Compare the GitHub release description for 0.39.1 with the other rules_go releases that include WORKSPACE snippets. Confirm whether the missing sha256 snippet is accidental, then update the release description if appropriate and verify that the WORKSPACE example is complete and consistent with neighboring releases.

Written by the indexing model from the issue text.