Use hyphens in documentation file names

[raph-luc]

Description of the modifications

Apparently better for search engines:

Useful links and references

https://developers.google.com/style/filenames

[hpohekar]

We can not import Python files with hyphens in their name. So instead of having both non imported file names with hyphens and imported file names without hyphens, we can follow the existing name format of using underscore for consistency.

Let's see, what other team members think.