doc(daemon): add doc for Handle and InternalHandle in types.d.ts

packages/daemon/src/types.d.ts

@@ -245,7 +245,19 @@ export type ProvideControllerForFormulaIdentifierAndResolveHandle = (
   formulaIdentifier: string,
 ) => Promise<Controller>;
 
+/**
+ * A handle is used to create a pointer to a formula without exposing
+ * it directly. For example, this is used to provide an EndoGuest with a
+ * reference to its creator EndoHost. By using a handle that points to the host
+ * instead of giving a direct reference to the host, the guest does not get
+ * access to the functions of the host. This is the external facet of a handle.
+ * It directly exposes nothing. The handle's target is only exposed on the internal facet.
+ */
 export interface Handle {}
+/**
+ * This is the internal facet of a handle. It exposes the formula id that the
+ * handle points to. This should not be exposed outside of the endo daemon.
+ */
 export interface InternalHandle {
   targetFormulaIdentifier: string;
 }