docs: add example from chalg

[machow]

This PR adds an example created by @chalg to the docs! Instead of expanding to show the code, it has two external links:

• Python: https://gist.github.com/chalg/93ca29e202ab86e7d4caad44726372e4/d17c1b4ba608ae1c3df6ac7fc377065ae5708ba7
• Post w/ R code: https://chalg.quarto.pub/carbon-intensity-of-electricity-consumption/

[codecov-commenter]

Codecov Report

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

Project coverage is 82.45%. Comparing base (38033ce) to head (488f853).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #323 +/- ## ======================================= Coverage 82.45% 82.45% ======================================= Files 41 41 Lines 4258 4258 ======================================= Hits 3511 3511 Misses 747 747 ```

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