Draft and add language about how data is collected by analytics, user accounts to cookie cutters

[hancush]

We want users of our websites to be aware of information we are and are not collecting about them, so they can make an informed choice whether to proceed. Let's draft some friendly copy about analytics (applicable to virtually all of our sites) and user accounts (where applicable), and add pages and nav items for both to our website templates. If we move forward with SSO / social authentication (#26), we should also draft language on the pros and cons of using a single account to access many websites and provide guidance on alternatives for folks who are not comfortable with so much of their internet use consolidated around one account.

Related to #265 / #266

h/t @fatima3558

Google has a decent example of explaining what data they collect and why.

[smcalilly]

here are some relevant resources:

• https://www.privacypolicies.com/
• https://github.com/Automattic/legalmattic