docs(Python): Add examples for polars.read_parquet and polars.read_parquet_schema

[GabrielBifano]

Added examples for the methods polars.read_parquet() and polars.read_parquet_schema()

This change is part of the issue: #13161, which has a good first issue label.

This is my first commit to the project, i followed the contribution guide, and took inspiration in other pull requests to be sure. Please let me know of any mistakes I've possibly made during the process.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 80.95%. Comparing base (fc3c663) to head (4824cc7).

❗ Current head 4824cc7 differs from pull request most recent head 3f7b9ba. Consider uploading reports for the commit 3f7b9ba to get more accurate results

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #14847      +/-   ##
==========================================
- Coverage   80.99%   80.95%   -0.05%     
==========================================
  Files        1330     1327       -3     
  Lines      172572   172081     -491     
  Branches     2453     2453              
==========================================
- Hits       139772   139300     -472     
+ Misses      32329    32311      -18     
+ Partials      471      470       -1     

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