Flowchart "Which type should i use"

Which datatype should i use flowchart, so that users can decide which datatype to use, illustrating core benefits of the datatype and introducing "custom array" and "custom csv" (follow up on discord conversation)

No file or test is named. Start by locating the existing datatype documentation and reviewing the referenced Discord discussion; define the flowchart's datatype choices and benefits, including custom array and custom CSV. Done means the documentation contains a usable flowchart that helps users choose a datatype and introduces both custom types.

Written by the indexing model from the issue text.