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/safety-cast-var.cs

@@ -0,0 +1,9 @@
+IUser user;
+
+// Here we can pre-define the actual declaration of said IGuildUser object,
+// so we don't need to cast additionally inside of the statement.
+if (user is IGuildUser guildUser)
+{
+    Console.WriteLine(guildUser.JoinedAt);
+}
+// Check failed.