Reorganise scripts in examples folders

[niksirbi]

I tried to put some order to the examples folder, this is what I came up with:

.
├── blackcap
│   ├── 1_source_images.py
│   ├── 2_prep_lowres.py
│   ├── 3_prep_highres.py
│   ├── 4_build_template.sh
│   └── 5_post_build.py
├── slurm
│   ├── batch_across_average_types.sh
│   ├── batch_across_templates.sh
│   ├── build_template.sh
│   └── post_build.sh
└── tadpole
    └── 1_downsample_source_images.py

The logic being that there is one "preprocessing" folder per species, and the scripts there-in are numbered in order of execution. SLURM scripts are separate, because in theory they can be very easily adapted cross-species.

This was mostly done to clear up my "mental workspace" in preparation for making new templates. Let me know if it makes sense.

This PR does nothing else than renaming/moving files, no code was changed.

[niksirbi]

Should be rebase to main after #44 is merged, to fix the linkcheck error.

[alessandrofelder]

I like this a lot, at least for now. We should make sure to avoid code duplication across species-specific scripts, to the extent possible - but this is a general and unrelated point.