Many people wonder how you could easily edit Lookup Table content by non-tech people and keep the process of updating and shipping that to Graylog as low as possible.
I have seen people writings scripts or automation doing this what adds another moving wheel to the setup and it can be a burden. Many already use Google Sheets or similar - why not try to use that direct?
In short - you can use the export CSV URL from a shared Google Sheet as source for a DSV Lookup:
In the linked Document you can see the different options as you can also run queries, remove headers and multiple more.
Do not forget to use Caching in Graylog if you use this Lookup Table in Graylog for all messages, or Google will block your Graylog from accessing this cause of a detected DDOS … (i just experienced this so, create at least a node based caching for this).