New Section for AWS Mistakes

[ThanosBaskous]

Common mistakes made by AWS users - especially new ones.

Categories for of mistakes by organization type - Startup vs Fortune 500 company

Mistakes WIP: https://quip.com/XIuQAcaClBVV

[lynnlangit]

To clarify the idea is to pool our thoughts via the Quip document, then format/export it to markdown, for inclusion via a pull request here -- likely as new section in the main document.