Merge pull request #3046 from ilianiliev-redis/using-full-row-format-and-mapping

[RDSC-5016] Improving documentation for using full row format and mapping

Author: andy-stark-redis

content/integrate/redis-data-integration/data-pipelines/transform-examples/redis-row-format.md

@@ -151,3 +151,5 @@ output:
           expression: concat([after.CITY, ', ', after.STATE])
           language: jmespath
     ```
+
+- When using the `full` row format, you should prepend all data fields in transformation and key calculations with `before` or `after` depending on whether you want to access the previous or current value of the row. The only exception to this is the `mapping` section where only the `after` values are available, so you should use the column/value name without the `after` prefix.