Revert "libical: temporarily don't build docs to unblock staging-next"
Revert "libical: temporarily don't build docs to unblock staging-next"

This reverts commit dae72e7e7dab5ae89d382471f4cccb888a5458e9.
Not needed now.

NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs