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/samples/casting.cs

@@ -0,0 +1,7 @@
+// Say we have an entity; for the simplicity of this example, it will appear from thin air.
+IChannel channel;
+
+// If we want this to be an ITextChannel so we can access the properties of a text channel inside of a guild, an approach would be:
+ITextChannel textChannel = channel as ITextChannel;
+
+await textChannel.DoSomethingICantWithIChannelAsync();