Add docs on how to add a new column to our Fastly logs and Athena
Add docs on how to add a new column to our Fastly logs and Athena

Co-authored-by: Bevan Loon <cc8f0a45e07051865acd0133bc4f092ec4dda7e7@digital.cabinet-office.gov.uk>

alphagov/govuk-developer-docs,alphagov/govuk-developer-docs,alphagov/govuk-developer-docs,alphagov/govuk-developer-docs