Add davinci_functions.explain(prompt)

Full Changelog: v0.1.3...v0.1.4

v0.1.3: Add `davinci_functions.function`

Full Changelog: v0.1.2...v0.1.3

v0.1.2: Initial release + Python 3.8 support (rev2)

add annotation

v0.1.1: Initial release + Python 3.8 support

support Python 3.8

v0.1.0: Initial release

Full Changelog: https://github.com/odashi/davinci-functions/commits/v0.1.0

Test release

Full Changelog: https://github.com/odashi/davinci-functions/commits/v0.0.1a1