[FEAT/script]: Document all scripts

[andthum]

Is your feature request related to a problem? Please describe.
Currently, only six scripts are documented in the official documentation (scripts/discretization/discrete_pos.py, scripts/structure/contact_hist.py, scripts/structure/lig_change_at_pos_change_blocks.py, scripts/structure/lig_change_at_pos_change_blocks_hist.py and the two script templates scripts/script_template.py and scripts/script_template_dtrj.py. The only way you can get help about the other scripts is the -h option (or asking the author).

Describe the solution you'd like
Add docstrings to all scripts and include them in the documentation.