Improvements to the low-cost optics module instructions

Working through these instructions revealed a couple of improvements that could be made.

1. The explaination and image could be more clear for step 3 (Push-fit the lens). A solution could be another image showing the correct and wrong side to go into the spacer, similar to how we show the correct and wrong camera cable further down the page.
2. Figuring out which way the camera platform is orientated is tricky. One solution might be to print it with an 'x' on the side that you can align with the instructions. This makes it more difficult for a user to put the camera and spacer on the wrong way round and have to redo this step later.