Update export-data.md

[JeffreyGroves]

Add a caveat that periodic backups must first be enabled on the database before the Export choice becomes available, as stated in step 3.

[rrelledge]

@JeffreyGroves I'm a little confused about this requested change. In the Cluster Manager UI, I am able to create a new database, and then click the Export option as mentioned in step 3 of https://redis.io/docs/latest/operate/rs/databases/import-export/export-data/#export-database-data without needing to enable periodic backups first.
Are you saying this Export option is greyed out or not selectable for you unless you set up periodic backups first? If so, what version of Redis Enterprise Software were you using?

[JeffreyGroves]

@rrelledge Thanks for looking into this. When I looked at the customer's SM, I didn't see the export option.
It was explained to me that before you can export that you first have to have periodic backups enabled. If that is not the situation, then there must have been some kind of UI bug going on.

[rrelledge]

@JeffreyGroves I noticed that you mentioned "SM" instead of "CM UI". Was the customer using Redis Cloud instead of on-prem Redis Enterprise Software in this case? If so, then the correct export page would be the Redis Cloud version: https://redis.io/docs/latest/operate/rc/databases/back-up-data/.

Based on the following excerpt, it seems that behavior might be expected and already documented for Redis Cloud:

Back up and export data on demand

After backups are turned on, you can back up your data at any time. Use the Backup now button in the Durability section.

Use the Backup Now button to make backups on demand.
You can only use the Backup now button after you turn on backups.