archipelago: Add info when retrying to get a lock
docs: Describe archipelago open/close mechanism
docs: Update archipelago packages

Update archipelago packages and installation procedure.
docs: Update archipelago config section
docs: Add archipelago v0.4 upgrade notes
docs: Remove numbers from sections
docs: Fix design doc index
docs: Update garbage collection design doc
docs: Separate install and admin's guide

Separate installation and administrator's guide.
Also include minor documentation fixes.
docs: Update administration_guide