Clarify coordinate values in `02_Meshes.ipynb`

In `02_Meshes.ipynb`, the mesh diagram includes example coordinate values underneath the image:

```text
node=94 : x/y = node_x/y[94] : 43.125 / 34.356213
node=97 : x/y = node_x/y[97] : 45.0 / 35.26439
```
It is not currently clear to learners what these values represent. The notebook should add a short caption or explanatory sentence stating what these values means. This would make the diagram easier to interpret without needing to modify the SVG itself. This was initially highlighted in Issue #258

Open 02_Meshes.ipynb and locate the mesh diagram containing the node=94 and node=97 coordinate examples. Add a short caption or explanatory sentence clarifying what the displayed coordinate values represent, without changing the SVG, then review the rendered notebook to confirm the explanation is visible and clear.

Written by the indexing model from the issue text.