Add more documentation

docs/operations/data_migration.md

@@ -697,3 +697,30 @@ Example: `cf ssh getgov-za`
 |   | Parameter                  | Description                                                                 |
 |:-:|:-------------------------- |:----------------------------------------------------------------------------|
 | 1 | **debug**                  | Increases logging detail. Defaults to False.                                |
+
+## Transfer federal agency script
+The transfer federal agency script adds the "federal_type" field on each associated DomainRequest, and uses that to populate the "federal_type" field on each FederalAgency.
+
+**Important:** When running this script, note that data generated by our fixtures will be inaccurate (since we assign random data to them). Use real data on this script.
+Do note that there is a check on record uniqueness. If two or more records do NOT have the same value for federal_type for any given federal agency, then the record is skipped. This protects against fixtures data when loaded with real data.
+
+### Running on sandboxes
+
+#### Step 1: Login to CloudFoundry
+```cf login -a api.fr.cloud.gov --sso```
+
+#### Step 2: SSH into your environment
+```cf ssh getgov-{space}```
+
+Example: `cf ssh getgov-za`
+
+#### Step 3: Create a shell instance
+```/tmp/lifecycle/shell```
+
+#### Step 4: Running the script
+```./manage.py transfer_federal_agency_type```
+
+### Running locally
+
+#### Step 1: Running the script
+```docker-compose exec app ./manage.py transfer_federal_agency_type```