Adds one line description and key queries in README

[JBAhire]

• Added one line description for GraphQL service.
• Added queries section which lists key queries across main screens including:
  • Get all traces in provided time range
  • Find trace using TraceID
  • Get all services your application is using
  • Get all backends your application is using
  • Get all API's your application is using
  • Get service and backend dependency graph

[codecov]

Codecov Report

❗ No coverage uploaded for pull request base (main@c06ef82). Click here to learn what that means.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             main      #12   +/-   ##
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  Coverage        ?   56.75%           
  Complexity      ?      196           
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  Files           ?       76           
  Lines           ?     1096           
  Branches        ?       29           
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  Hits            ?      622           
  Misses          ?      453           
  Partials        ?       21           

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