Cookbook for Perlin noise

[TilmanMay]

Added a cookbook explaining the perlin noise feature, as Menno said, this would be good for documentation purposes.
#916 followup

[github-actions]

Benchmark	Main	Feature	Difference (99.9% CI)
Slab interpolation simple none	1.285 ± 0.006 (s=357)	1.286 ± 0.008 (s=346)	-0.1% .. +0.2%
Slab interpolation curved simple none	1.287 ± 0.006 (s=335)	1.286 ± 0.007 (s=367)	-0.2% .. +0.1%
Spherical slab interpolation simple none	1.194 ± 0.011 (s=411)	1.193 ± 0.011 (s=346)	-0.3% .. +0.1%
Slab interpolation simple curved CMS	1.321 ± 0.006 (s=339)	1.321 ± 0.008 (s=345)	-0.1% .. +0.1%
Spherical slab interpolation simple CMS	1.604 ± 0.015 (s=297)	1.605 ± 0.009 (s=266)	-0.1% .. +0.3%
Spherical fault interpolation simple none	1.267 ± 0.009 (s=345)	1.265 ± 0.006 (s=368)	-0.3% .. +0.0%
Cartesian min max surface	3.057 ± 0.013 (s=143)	3.064 ± 0.013 (s=154)	+0.0% .. +0.4%
Spherical min max surface	8.571 ± 0.092 (s=57)	8.576 ± 0.090 (s=50)	-0.6% .. +0.8%

[danieldouglas92]

Hey @TilmanMay, thanks for adding this, it looks great! The figures are very pretty and the documentation in your README is clear. Aside from a few typos, my only comment is that your figure captions aren't being formatted correctly in the built doc. See my comments on the README for how to fix this.

[danieldouglas92]

I imagine this is supposed to be a figure caption, but in the built docs it does not render that way. To have this be a figure caption, you have to include it between the ::: :::, so it would look like this:

:::{figure} normal_field.png
:name: perlin_noise_normal_field
:alt: Normal temperature field (without noise)
:align: center

Normal temperature field without added disturbances
:::

[danieldouglas92]

Suggested change

	This example contains a simple mantle features with its temperature field disturbed. Perlin noise is used to introduce realistic, multi-scale variations in both temperature and composition fields.
	This example contains a simple mantle feature with a disturbed temperature field. Perlin noise is used to introduce realistic, multi-scale variations in both temperature and composition fields.

[danieldouglas92]

Suggested change

	- `persistence`: Amplitude multiplier for each octave (e.g., `amplitude *= persistence`, default: 0.5). So the next layers impact of the overall field is have as small.
	- `persistence`: Amplitude multiplier for each octave (e.g., `amplitude *= persistence`, default: 0.5). So the next layers impact of the overall field is halved.

[danieldouglas92]

Please add a changelog entry for this as well!