tsnet: link in feature/acme by default

This was missing in the earlier f5eac39ea7 and meant that tsnet users weren't
getting (all of) acme support.

Thanks to @ChaosInTheCRD and @BeckyPauley for debugging.

Updates #12614
Updates #20252

Change-Id: I176a7b179b2ad3726aca484057f0aae7cc3561c8
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
This commit is contained in:
Internal Server Error - Gitea: Git with a cup of tea
500 Internal Server Error

Gitea Version: 1.28.0+dev-477-g8b6ad49a5f