[Docs RFC] Unite and rewrite the write, query and ingest data sections about docs HOT 1 OPEN

I think we can remove ingesting data from Prometheus. While it's possible to do via some third party tool, it's not a use case that we support well since we stopped the work on Promscale.

the current write data page is for single or 10s of rows ingested. For larger batches, 100+ rows we should point to using COPY (new documentation)

Another common way to get data into a database is by using a CSV, especially at the beginning, so we should also make it easy to find.

Then we can have other more complex ways of getting data in.

For Upserting batches of data, engineering recommended using doing COPY to a temp table and them inserting into the final table via an insert query. Engineering will need to provide the best recommendation for this.

from docs.