Add support for insert CSV

[CBroz1]

• For insert method, check if object is pathlib.Path. If so, load as comma-delimited data
• Modify test to run this method
• Pass tests
• Edit root README to reflect change from sphinx to mkdocs
• Add documentation for new feature (add inserting various data types)

[dimitri-yatsenko]

Looks great! Thanks! Please update the CHANGELOG and we'll merge.

[dimitri-yatsenko]

Would it make sense to also accept the filepath in the form of a str as well as pathlib.Path?

[CBroz1]

Please update the CHANGELOG and we'll merge.

Updated

Would it make sense to also accept the filepath in the form of a str as well as pathlib.Path?

My thought process was that a pathlib object is unambiguous. But I can adjust if you prefer accepting filepaths as strings. Is there any case where we would want to accept data as a string?