Adding Entity guides, flowcharts, better sample system. (#2054)

* initial

* Interaction glossary entry

* Sharded Interaction sample

* Renames into solution

* Debugging samples

* Modify target location for webhookclient

* Finalizing docs work, resolving docfx errors.

* Adding threaduser to user chart

* Add branch info to readme.

* Edits to user chart

* Resolve format for glossary entries

* Patch sln target

* Issue with file naming fixed

* Patch 1/x for builds

* Appending suggestions

docs/guides/entities/introduction.md

@@ -0,0 +1,87 @@
+---
+uid: Guides.Entities.Intro
+title: Introduction
+---
+
+# Entities in Discord.Net
+
+Discord.Net provides a versatile entity system for navigating the
+Discord API.
+
+> [!TIP]
+> It is **vital** that you use the proper IDs for an entity when using
+> a `GetXXX` method. It is recommended that you enable Discord's
+> _developer mode_ to allow easy access to entity IDs, found in
+> Settings > Appearance > Advanced. Read more about it in the
+> [FAQ](xref:FAQ.Basics.GetStarted) page.
+
+## Inheritance
+
+Due to the nature of the Discord API, some entities are designed with
+multiple variants; for example, `IUser` and `IGuildUser`.
+
+All models will contain the most detailed version of an entity
+possible, even if the type is less detailed.
+
+## Socket & REST
+
+REST entities are retrieved over REST, and will be disposed after use.
+It is suggested to limit the amount of REST calls as much as possible,
+as calls over REST interact with the API, and are thus prone to rate-limits.
+
+- [Learn more about REST](https://restfulapi.net/)
+
+Socket entities are created through the gateway,
+most commonly through `DiscordSocketClient` events.
+These entities will enter the clients' global cache for later use.
+
+In the case of the `MessageReceived` event, a
+`SocketMessage` is passed in with a channel property of type
+`SocketMessageChannel`. All messages come from channels capable of
+messaging, so this is the only variant of a channel that can cover
+every single case.
+
+But that doesn't mean a message _can't_ come from a
+`SocketTextChannel`, which is a message channel in a guild. To
+retrieve information about a guild from a message entity, you will
+need to cast its channel object to a `SocketTextChannel`.
+
+> [!NOTE]
+> You can find out the inheritance tree & definitions of various entities
+> [here](xref:Guides.Entities.Glossary)
+
+## Navigation
+
+All socket entities have navigation properties on them, which allow
+you to easily navigate to an entity's parent or children. As explained
+above, you will sometimes need to cast to a more detailed version of
+an entity to navigate to its parent.
+
+## Accessing Socket Entities
+
+The most basic forms of entities, `SocketGuild`, `SocketUser`, and
+`SocketChannel` can be pulled from the DiscordSocketClient's global
+cache, and can be retrieved using the respective `GetXXX` method on
+DiscordSocketClient.
+
+More detailed versions of entities can be pulled from the basic
+entities, e.g., `SocketGuild.GetUser`, which returns a
+`SocketGuildUser`, or `SocketGuild.GetChannel`, which returns a
+`SocketGuildChannel`. Again, you may need to cast these objects to get
+a variant of the type that you need.
+
+### Sample
+
+[!code-csharp[Socket Sample](samples/socketentities.cs)]
+
+## Accessing REST Entities
+
+REST entities work almost the same as Socket entities, but are much less frequently used.
+To access REST entities, the `DiscordSocketClient`'s `Rest` property is required.
+Another option here is to create your own [DiscordRestClient], independent of the Socket gateway.
+
+[DiscordRestClient]: xref:Discord.Rest.DiscordRestClient
+
+### Sample
+
+[!code-csharp[Rest Sample](samples/restentities.cs)]