Updated Readme example to fix serving and use class api

[ahmadnazeri]

Description

Type of change

Does this correspond to an open issue?

Select type(s) of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update

Checklist:

• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• I have fixed any merge conflicts

[codecov]

Codecov Report

Merging #792 (155a765) into main (6f7b498) will decrease coverage by 0.21%.
The diff coverage is 55.38%.

@@            Coverage Diff             @@
##             main     #792      +/-   ##
==========================================
- Coverage   59.71%   59.50%   -0.21%     
==========================================
  Files          63       66       +3     
  Lines       12408    12972     +564     
==========================================
+ Hits         7409     7719     +310     
- Misses       4232     4476     +244     
- Partials      767      777      +10     

Impacted Files	Coverage Δ
coordinator/coordinator.go	42.67% <0.00%> (-0.13%)	⬇️
helpers/compression/compression.go	0.00% <0.00%> (ø)
provider/k8s.go	27.92% <ø> (-2.29%)	⬇️
provider/provider_config/spark_config.go	58.89% <ø> (+1.84%)	⬆️
provider/provider_type/provider_type.go	100.00% <ø> (ø)
provider/redshift.go	85.24% <ø> (ø)
provider/spark.go	23.25% <ø> (+4.67%)	⬆️
provider/sql.go	65.47% <ø> (-0.31%)	⬇️
runner/worker/worker.go	78.57% <ø> (ø)
serving/serialize.go	74.81% <ø> (-19.58%)	⬇️
... and 7 more

... and 12 files with indirect coverage changes

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