Add tracking pixel to Flyte README and docs

[neverett]

Why are the changes needed?

• Fixes tracking pixel in docs -- I copied the wrong one in https://github.com/flyteorg/flyte/pull/5336
• Adds tracking pixel to Flyte README

Check all the applicable boxes

• [ ] All new and existing tests passed.
• [ ] All commits are signed-off.

Docs link

TK

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 61.09%. Comparing base (43c0f1a) to head (4fdb830).

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #5338      +/-   ##
==========================================
- Coverage   61.10%   61.09%   -0.01%     
==========================================
  Files         794      794              
  Lines       51213    51213              
==========================================
- Hits        31292    31289       -3     
- Misses      17039    17043       +4     
+ Partials     2882     2881       -1     

Flag	Coverage Δ
unittests-datacatalog	69.31% <ø> (ø)
unittests-flyteadmin	58.86% <ø> (-0.05%)	:arrow_down:
unittests-flytecopilot	17.79% <ø> (ø)
unittests-flytectl	68.30% <ø> (ø)
unittests-flyteidl	79.30% <ø> (ø)
unittests-flyteplugins	61.94% <ø> (ø)
unittests-flytepropeller	57.32% <ø> (ø)
unittests-flytestdlib	65.75% <ø> (+0.07%)	:arrow_up:

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[neverett]

Superseded by https://github.com/flyteorg/flyte/pull/5341