I would suggest to rethink your ignite suggestion. The problem is it's range. Very often when you're attack from max range you're simply not in range for ignite. Ignite is okay for adc's with a low range like vayne and sivir but Caitlyn can use something that benefits her more. I recently started using cleanse, it's a good option to offer you a lot of extra survivability since u can remove some cc's with it. It will help you a lot in teamfights and thus a better choice on the long if you know how to time it. It can also help you vs some adcs with a cc such as vayne or ashe.

Not going to vote until the guide is complete, but until then, here are my criticisms.

1. Double Desolation Runes sacrifices a lot of potential lane dominance. I'd suggest running atleast one set of strength runes, either the marks of the quintessences for the lane dominance, harassing, last hitting, etc. Also, just look at Q's scaling ratio with AD, take advantage of it.

2. I don't value greater seal of replenishment either, since you sacrifice some ability to trade with champions who run Greater Seal of Armor instead. The last thing you want to do as Caitlyn is get outtraded, since she excels at dominating lanes with her range. Consider managing your mana a little differently and using more auto-attack harass from afar instead of frequent Q spamming to dominate. (So between points 1 and 2 together, you're sacrificing A LOT of lane dominance for a little more sustain and some additional flat armor penetration.)

3. Separate the coming Gameplay section into atleast Laning, and Teamfighting sections, since they're both significantly varied in how they're played and require specific strategies as a Caitlyn player. Additionally, your guide will benefit as a whole since you'll be including more information on How to play Caitlyn instead of just how to build her.

Good luck with the remainder of your guide :D