Updates to walkthrough

[MisterJames]

Added a couple of clarifications, things I ran into in walking through the tutorial.

• location of code block in step 1
• note on cookie expiry in step 3

Looks like github is also picking up some encoding change and has a bunch of misses from step 4 on. Hope that's alright.

[blowdart]

I didn't have notifications turned on sigh I've updated for RC2 - and changed some wording, does this address your concerns?