doc/builders/packages/xorg: Use ShellSession for shell.
doc/builders/packages/xorg: Use ShellSession for shell.

I was worried, but the HTML output can still be copy-and-pasted, so it's
not a problem.

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