282: Update and clean up some getting started docs (#3916)

* Update and clean up some getting started docs

I made some changes based on Jonathan's suggestions. The big issue was that the
documentation about running "make dockerupdatedata" was after the link sending
you off to the webapp documentation, so he missed it. This fixes that flow and
adds some more details which are probably helpful to know.

* Improve Quickstart by adding more context explanation

* Clean up tools install section of Getting Started

* Add warnings about outdatedness