Better document the various protocols and classes involved in dealing with room timelines.

ElementX/Sources/Services/Timeline/TimelineProxyProtocol.swift

@@ -37,7 +37,9 @@ enum TimelineProxyError: Error {
     case failedPaginatingEndReached
 }
 
-// sourcery: AutoMockable
+/// Element X proxies generally wrap the counterpart RustSDK objects while providing platform specific
+/// interfaces. In this case it composes methods for interacting with a room's timeline and should be used alongside
+/// the ``TimelineItemProviderProtocol`` which offers a reactive interface to timeline changes.
 protocol TimelineProxyProtocol {
     var timelineItemProvider: TimelineItemProviderProtocol { get }
     
@@ -125,3 +127,6 @@ protocol TimelineProxyProtocol {
                                 html: String?,
                                 intentionalMentions: Mentions) -> RoomMessageEventContentWithoutRelation
 }
+
+// sourcery: AutoMockable
+extension TimelineProxyProtocol { }