Adds admin documentation and a changelog entry for two-phase student reg
Fixes up some formatting for two-phase
Some more tweaks to two-phase docs formatting
Tweaks image widths
Adds priority_limit and links to full docs in changelog for two-phase
Links directly to appropriate section of program modules docs
Clarifies how to edit 'priority_limit' in SCRMI
Moves two-phase docs location in release documentation
Merge pull request #1089 from learning-unlimited/two-phase-docs

Adds documentation for Two-Phase Student Registration