Docs refactor

[giovanniborella]

Multiple changes incomming, please SQUASH when adding to master!

I have cleaned up docs a bit, to make it more expandable and behave better in the UI.

current:

Proposed:

Following is a curated list of the changes made:

• Re-organized files and indexes to support grouping of pages in the sidebar
• Added a script for aligning headers, stick to 2 levels: === for headers, and --- for subheaders.
• Create a template for describing extenstions and their parameters. take a look at otp
• Move the passage about serviceworkers from readme to its own page, added information on setting urlsIgnoredForCaching
• Fix multiple typos and warnings in sphinx
• Remove version from each file, information was superflorious.
• Remove date from each file, added in footer instead - it showed build time, not when the page was written.