Updating readme with additional details

[sohilpandya]

• Added missing quick start info
• added overview section that contains information about the deployment and migrations.
• removed deployment section as it is out of date/not necessary

fixes #636

[codecov-io]

Codecov Report

Merging #650 into staging will not change coverage. The diff coverage is n/a.

@@           Coverage Diff            @@
##           staging     #650   +/-   ##
========================================
  Coverage    94.48%   94.48%           
========================================
  Files          132      132           
  Lines         2958     2958           
  Branches       519      519           
========================================
  Hits          2795     2795           
  Misses         163      163

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[sohilpandya]

I've updated as you'd asked and it's ready for review