maxing you 2. is not mandatory, many pros max E 2nd krepo, edward.

Their reasoning is that you don't need the stun again if your E isnt up anyway.
Personally I max Q since you'll be able to use it faster in teamfights n such, but saying it's wrong isnt right.

Other than that, too lazy too read the guide, seems to have potential tho, I might come back later

Overall a decent guide, but with a few major flaws. Will write a more extensive comment on that when I have time later this afternoon.
Just wanted to say this: Best combo on leona =

(ult)
e-q
(ult)
exhaust/ignite
flash-q
e-q

Basically, the flash allows you to have an extra gap closer for your Q, which (if you max it second - you should), has about half the cooldown your E has.

Incomplete cheat sheet. Also, Lulu is 5/5 and a hard counter to Leona. You forgot Taric.

Looks pretty nice, but there could be some improvements, I recommend you put the mastery page and runes on the cheat sheet. Other than your cheat sheet, I really like the guide. It looks very nice. But there are also some walls of text. I know they are probably good info but you could improve the look there. I haven't really tested it out and I don't know how well it would work (it will probably work but I am too lazy to test it). I will hold my vote until you improve the cheat sheet.