trunk -> master

Dependencies

• [2] KBW3FDZ2 Merge remote branch 'remotes/origin/master'
• [3] EKNK5AHQ doc: Augment the "Installation" section with material by Visser & Dolstra.
• [4] GYPHTT4M Manual: Remove tabs, indent consistently

Change contents

• replacement in doc/manual/installation.xml at line 97
  [2.1276]→[2.1276:1351](∅→∅)
  − nix-channel --add http://hydra.nixos.org/jobset/hydra/trunk/channel/latest
  [2.1276]

  [2.1351]
  + nix-channel --add http://hydra.nixos.org/jobset/hydra/master/channel/latest