I have no doubt that if Watership Down had been written today by an indie author, instead of the book itself having little notes to help us understand the terms used by rabbits and their thoughts (or seeing them used throughout the work), You would have to go to Richard Adams' personal blog to find out what an Owsla is supposed to be or what the name Hyzenthlay means.
This is actually a minor complaint. For the love of all that is good and sacred in this world, DO NOT MAKE YOUR READERS DEPENDENT ON MATERIAL OUTSIDE THE WORK ITSELF IN ORDER TO UNDERSTAND IT. KEEP YOUR IMPORTANT COMMENTS ABOUT THE LORE TO YOURSELF SO THAT THE PRODUCT ITSELF CAN EXPLAIN IT.
I've seen this too much with many authors today, it's always because of outside comments or a blog where all the basic and relevant material I need to know about the work is hidden under a blog aside of the main media, and that sucks. Let me discover it myself, let me theorize about it, for Lord's sake.
I understand that you often have this great desire to explain your whole world. There are times when I just want to throw in the whole explanation of the history of my projects, even if no one will read it, just because I want to talk about it, but no. Don't do that. Let your projects develop slowly on their own, let the viewer discover what you want to say and tell by reviewing each page, each chapter, and each dialogue itself. It's actually much more rewarding to get it right little by little rather than all at once.
Remember the main rule: show, don't tell.
And if you don't think it's necessary, what do you want them to know about your world and its story in the same work? It's not just a secondary piece of information about this background character, but often they are relegating information about characters and events or things that should be very important to the story itself, or even essential elements of their world (who is this, why are they called that, what is this, etc.). Then you just make your story to be absolutely nothing at all aside of a "bunch of words" with "characters" moving on it.