Docs: "How to add a data source"

[peterdudfield]

Add documentation on how to add a data source

Detailed Description

Would be useful having a little readme on how to add a data source (I know there probably arent any immedatie plans to add any, but think this still can be useful for understand everything)

Context

• This will make it easier to add a new data source
• Make it to understand all the connected files and structures
• Useful understand for when the predictions runs live

Possible Implementation

read me files in data source folder

1. create .zarr file
2. add location to config
3. create test data
4. create new data source class with these properties ....
5. ....

[JackKelly]

Sounds great! We might want to wait until after we do #90 as that might slightly change the way the DataSources work (but probably not very much!). #90 should definitely get rid of the need for intermediate Zarr stores.

[peterdudfield]

Yea, and it may also be influences by #166