Improved docstrings for user-facing functions

[fonnesbeck]

Description

Added more robust docstrings and removed the Elemwise docstring that was appended to each function.

Related Issue

• [x] Closes #292
• [ ] Related to #

Checklist

• [x] Checked that the pre-commit linting/style checks pass
• [ ] Included tests that prove the fix is effective or that the new feature works
• [x] Added necessary documentation (docstrings and/or example notebooks)
• [ ] If you are a pro: each commit corresponds to a relevant logical change

Type of change

• [ ] New feature / enhancement
• [ ] Bug fix
• [x] Documentation
• [x] Maintenance
• [ ] Other (please specify):