added new movement datasets figure, with caption

[niksirbi]

Closes #250.

I updated the figure to show both poses and bboxes datasets, as discussed. I also added a little caption. This is how it displays:

[codecov[bot]]

Codecov Report

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

Project coverage is 99.77%. Comparing base (3df12a9) to head (f8e5a97). Report is 1 commits behind head on main.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #286 +/- ## ======================================= Coverage 99.77% 99.77% ======================================= Files 14 14 Lines 883 883 ======================================= Hits 881 881 Misses 2 2 ```

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[sonarcloud[bot]]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

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