Add Guide for Discussions

[dbouwman]

Build a Guide page in that provides an intro to the concepts, and shows a few common flows

• create a discussion around an item
• get all posts for the item
• get specific user's posts for the item
• search posts for the item for a term
• create, reply, react to posts
• remove post

I think a lot of the intro content can be pulled from the Confluence Page (https://confluencewikidev.esri.com/display/Hub/Discussions+Architecture+Milestone+Review) but since this is an open source project, it would be really good to have this in the doc / repo vs Confluence

It would also be good to either have the Channel Model doc'd on the IChannel page and similar for IPost, and IReaction

Another thing that's currently hard to determine is what are the checks / validations and where are they applied. What's checked at the API vs what should be checked in the UI etc

This should be written so that any developer on our team can understand the conteps, how they map into the AGO entities and security model, and how to get started with the code.

[ajturner]

The new Hub.js Discussions Guide will be useful for devs using this subsystem.

This issue enumerates some suggested additions to the guide

• as I'm reading the guide, how do I get to the Discussions API
  • Add intro text to API docs
  • Hyperlinks to referenced methods interfaces
  • Add links to AGO API documentation as appropriate (e.g. groups)
• Add data model / domain diagram of relationships between objects
• Introduction
  • Move "Using hub-discussions" to beginning
• Reactions
  • move examples of adding reactions to a post to Reactions section
• Search
  • Add simple guide for Search: what properties allow search and regex guidance
• Other
  • Is Public not supported now? from Following along, other channel types not yet implemented will include "shared", "org", and "public".
  • does PostStatus have any restrictions on who can set it? Meaning can an author override moderation and set status to approved?
  • Add guidance on errors. e.g. sending invalid body, API down, non-existent channel

[tomwayson]

Great start.

The domain model is linked to ArcGIS Online users through Channels --

Suggest: "Discussions are linked to ArcGIS Online users through Channels --"

Under "Creating Posts", I suggest swapping the first and second examples (i.e. first show w/ a known channel id, then explain that if you have permissions, you can create a channel w/ an initial post in a single call).