Documentation : Auto and UUID

[AV25242]

Questions around "how to generate UUID for a field " pops up quite often. Its difficult to infer this information from the current documentation.

Add exclusive section in the documentation which is searchable and at the same time has example around it. as an example for a field _id to use UUID its as simple as attributing it as auto : 'uuid'

_id: { type: String, required: true, auto: ‘uuid’ }