Feat: add demo notebook

[codecov-commenter]

Codecov Report

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

Project coverage is 97.78%. Comparing base (b841b0d) to head (80773a0). Report is 16 commits behind head on main.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #19 +/- ## ======================================= Coverage 97.77% 97.78% ======================================= Files 9 10 +1 Lines 270 271 +1 ======================================= + Hits 264 265 +1 Misses 6 6 ``` | [Flag](https://app.codecov.io/gh/hnu-digihealth/patho-pix/pull/19/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=hnu-digihealth) | Coverage Δ | | |---|---|---| | [unittests](https://app.codecov.io/gh/hnu-digihealth/patho-pix/pull/19/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=hnu-digihealth) | `97.78% <100.00%> (+<0.01%)` | :arrow_up: | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=hnu-digihealth#carryforward-flags-in-the-pull-request-comment) to find out more.

:umbrella: View full report in Codecov by Sentry.
:loudspeaker: Have feedback on the report? Share it here.