Update cloud-config.md to include expected file format

Clarify root-level keys. Use page structure to indicate expected values.
Update cloud-config.md option descriptions

Re-word a few more things to look more like docs.
Update cloud-config.md based on feedback
Update cloud-config.md to use "parameter", not "option"
Update cloud-config.md - use "you"
Merge pull request #77 from chexxor/master

Update cloud-config.md to include expected file format