Documentation on How To Implement a New Provider

[juftin]

Is your feature request related to a problem? Please describe.

Camply aims to support new local, state, federal, and international camping providers. Currently, there isn't any centralized documentation on this process or an extremely clean provider to be used as an example. Now that ReserveCalifornia has been implemented we have a somewhat simple provider implementation contained within a PR - this is a great example for future providers.

Describe the solution you'd like

Create a clean documentation guide on how to create a new provider. This guide needs to cover the following details:

• Implementing an ABC Provider Class
• Implementing the corresponding ABC Search Class
• Integrating the new provider/search into the CLI
• Documenting usage of the new provider
• Link to the aforementioned PR to demonstrate