lp1744756 Docs fix and Permission change

lp1744756 Docs fix and Permission change

- Introduce MANAGE_CUSTOM_PERM_GRP_TREE permission.

- Remove unnecessary references to unused "disabled"
field for pgtdes.

- Update documentation to correctly explain how removing
and adding display entries works.

 Changes to be committed:
	modified:   Open-ILS/examples/fm_IDL.xml
	modified:   Open-ILS/src/sql/Pg/006.schema.permissions.sql
	modified:   Open-ILS/src/sql/Pg/950.data.seed-values.sql
	modified:   Open-ILS/src/sql/Pg/upgrade/XXXX.schema.perm-group-display.sql
	modified:   Open-ILS/web/js/ui/default/staff/admin/local/permission/app.js
	modified:   Open-ILS/web/js/ui/default/staff/circ/patron/regctl.js
	modified:   docs/RELEASE_NOTES_NEXT/Client/pgtde.adoc

Signed-off-by: Kathy Lussier <klussier@masslnc.org>