Add Developing OOD within OOD page

[Oglopf]

A discourse came in from a user wanting to do development work on ood and the dashboard at their center. We at OSC have a pretty standard workflow around this that is not documented and would therefore hinder dashboard development as the community is not aware of the setup possibly.

The discourse is here:
https://discourse.openondemand.org/t/best-practice-for-ood-configuration-change-out-of-production/3123/8

Proposal

• add a section under tutorials lableled "OOD Dashboard Development"
• in that section present the needed symlink setup and env variables as detailed in the discourse thread to allow the dev dashboard to take its own configs.
• include notes around what can be worked on through this and make sure to catch obvious can't cases.
• provide a small example to demonstrate some new routes, a new app, and customized look of the dev dashboard.