Linking poetry tool on getting started section of documentation

[diosmiodio]

For folks who aren't super familiar with python, might save them some time down the road. Saw it after I checked out the contribution guidelines, but I figure most people will start with getting started :)

[codecov[bot]]

Codecov Report

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

Project coverage is 81.43%. Comparing base (0665f5b) to head (e041124).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #1915 +/- ## ======================================= Coverage 81.43% 81.43% ======================================= Files 193 193 Lines 18604 18604 Branches 4032 4032 ======================================= Hits 15150 15150 Misses 3173 3173 Partials 281 281 ```

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