Merge branch 'doc_radial_strip_det' into 'f-update-manual-structure'

## Radial Strips

Radial strip detectors feature a trapezoidal shape with curved edges and radial geometry – the strips on such a sensor are arranged in a fan-like geometry, pointing to a common focal point. Shape, size and segmentation of a radial strip detector are defined using four parameters, each passed as an array with the number of elements equal to the number of strip rows:

- `number_of_strips`

- `angular_pitch`

- `inner_pitch`

- `strip_length`

Additionally, model parameters have to be set to `type = monolithic` and `geometry = radial_strip`. Due to the complexity of the geometry, this detector model currently doesn't allow the creation of passive support structures.

For radial strip detectors, the coordinate origin is placed in the centre of concentric arcs, which form the strip row edges, to enable easier transformation to polar coordinates utilized by the detector model's member functions.

![](./radial_params.png)

The optional parameter `stereo_angle` can be used to shift the strip focal point around the center of the sensor to create an asymmetrical sensor. By default, the stereo angle is disabled.

![](./radial_stereo_angle.png)

An examples of radial strip detector model implementation can be seen in `models/atlas_itk_r0` and further in the `examples/atlas_itk_petal` example.

[@hexagons]: https://www.redblobgames.com/grids/hexagons/