documentation - env vars and how to run dataset_ingress_v1

[mikeAdamss]

What is this

• We need a list of env vars added to a table in the base of the repo to specify what env vars are in used by the pipelines as a "Configuration" table. Dont include webhook urls please, its a public repo. Here's an example markdown table for reference: https://github.com/ONSdigital/dp-dataset-api.

• We need some documentation on how to run data_ingress_v1. Please put this in a readme in the ./dpypelines/pipeline` sub directory please (if there's an existing readme get it rid of it please, we need some clearer documentation). For context if you point it at a directory with a correct config file and some data on your local machine it should work. Please inlcude a high level description of what this function does.

NOTE - not a full user guide on how the code works, this is "how do you use it", starting from data_ingress_v1().

• Can you check the readmes and remove any (really old) references to pipeline-config please.