Add privacy and cookies link to documentation website

[victordibia]

Why are these changes needed?

Add privacy and cookies link to documentation website, to provide information on the associated privacy policy.

Related issue number

Checks

• I've included any doc changes needed for https://microsoft.github.io/autogen/. See https://microsoft.github.io/autogen/docs/Contribute#documentation to build and test documentation locally.
• I've added tests (if relevant) corresponding to the changes introduced in this PR.
• I've made sure all auto checks have passed.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (3a768c3) 26.63% compared to head (7292a45) 26.63%.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #966   +/-   ##
=======================================
  Coverage   26.63%   26.63%           
=======================================
  Files          28       28           
  Lines        3777     3777           
  Branches      858      858           
=======================================
  Hits         1006     1006           
  Misses       2700     2700           
  Partials       71       71           

Flag	Coverage Δ
unittests	26.58% <ø> (ø)

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[afourney]

LGTM