There are a couple of issues that need to be addressed about your edits to the Joker (Prime Earth) page.
First, whenever you include a quote, you must add the source, meaning the comic where the quote comes from. That's what the | QuoteSource field is for.
Second, there's the rebirth paragraph. All that info that you included happened both in JL #50 and the DC Universe Rebirth Special and in both books, Joker was not featured and the mysterious revelation adds nothing to the character's development, especially since DC has used it as a selling gimmick and has not made any developments on the subject. The point is that we try to include only vital information about events and situation that the character is involved with and which represents anything important. Joker doing some random crimes and being taken to Arkham is not something unusual or important, therefore it is not needed on the character's page. That information is much more useful in the comic book article. As for the three Jokers stuff, it would be better to include a note, but not until there is more information about it.
That's all for now. If you have any questions, feel free to ask.