[DOCS]: Add dedicated scarf tracking pixel to readme

[cmarteepants]

This adds website analytics to the Cosmos readme.

Note that while you cannot explicitly opt out of website analytics for the publicly hosted readme (and docs), Scarf respects browser DND. If that is set via the browser, telemetry for that user will not be sent to Scarf.

Scarf privacy policy: https://about.scarf.sh/privacy-policy
Astronomer privacy policy: https://www.astronomer.io/privacy/

[netlify]

✅ Deploy Preview for sunny-pastelito-5ecb04 canceled.

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[netlify]

✅ Deploy Preview for sunny-pastelito-5ecb04 canceled.

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🔍 Latest deploy log	https://app.netlify.com/sites/sunny-pastelito-5ecb04/deploys/670eab2b4f9f5200089ca9ad

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 95.73%. Comparing base (e81b94f) to head (e5bae55).
Report is 2 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1256   +/-   ##
=======================================
  Coverage   95.73%   95.73%           
=======================================
  Files          67       67           
  Lines        3965     3965           
=======================================
  Hits         3796     3796           
  Misses        169      169           

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