Improve documentation

Since the current documentation lacks some important details for users and might make using foolbox harder than it has to be, we should improve this.
Let us collect suggestions for what to improve by either posting the ideas or linking the respective issues.

Review the existing Foolbox documentation and the issue thread first to identify concrete missing details or linked issues. Done means narrowing this broad request to a specific documentation change with a clear location and acceptance criteria.

Written by the indexing model from the issue text.