Use absolute URLs for failing links in docs/index.md

[pankajkoti]

When running hatch run docs:build locally, warnings are reported indicating that the linked pages for LICENSE and PRIVACY_NOTICE cannot be found. This occurs because those GitHub pages are outside the context of the built and shipped documentation, leading to errors when clicking those links. To address this, I am updating the links to use absolute GitHub URLs to correctly locate these files.

The warning message is as below:

INFO    -  Building documentation to directory: /Users/pankajkoti/astronomer/dag-factory/site
INFO    -  Doc file 'index.md' contains an unrecognized relative link '../LICENSE', it was left as is.
WARNING -  Doc file 'index.md' contains a link '../PRIVACY_NOTICE.md', but the target is not found among documentation files.

And clicking on those links in the served docs, gives an error as shown in below screenshot:

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 93.31%. Comparing base (a53c765) to head (f9922c3).
Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #331   +/-   ##
=======================================
  Coverage   93.31%   93.31%           
=======================================
  Files          10       10           
  Lines         778      778           
=======================================
  Hits          726      726           
  Misses         52       52           

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