Add section for key Brigade roles
Fix heading hierarchy
Deprecate the 'Team Structure' section
Add section "How to host a hack night" and create new category for menu "How to..."
Add section "How to collaborate with government"
Update index to Guides and insert placeholder text for sections which are "to do"
Merge pull request #2 from dgroch/master

Add a few sections, update index and insert placeholder text for "to do" sections