docs: call out environment scoping of synchronised segments

Author: Zaimwa9

docs/docs/third-party-integrations/cohort-synchronisation/amplitude.md

@@ -42,6 +42,14 @@ application uses as the Flagsmith [identity](/flagsmith-concepts/identities) ide
 
 ![Amplitude Flagsmith destination configuration](/img/cohort-synchronisation/amplitude-destination-config.png)
 
+:::warning The key decides the environment
+
+Every cohort sent to this destination is synchronised into the environment its key belongs to, and nothing in Amplitude
+shows which one that is. To synchronise cohorts into a second environment, create a key there and add a second Flagsmith
+destination for it.
+
+:::
+
 ## 3. Synchronise a cohort
 
 1. In Amplitude, open the cohort you want to target and click **Target users**.

docs/docs/third-party-integrations/cohort-synchronisation/csv-import.md

@@ -26,14 +26,21 @@ Other columns are ignored, so you can upload an export without stripping it down
 1. Go to the **Segments** page in your project and click **Create Segment**.
 2. Choose **From a CSV list**.
 3. Give the segment a name and, optionally, a description.
-4. Select the environment the identities should be targeted in. The segment will only have members in that environment.
+4. Select the environment the identities should be targeted in.
 5. Drag your CSV file onto the upload area, or click **Select file** to browse for it.
 6. Check the **Identifier column** that Flagsmith has picked, and change it if the identifiers are in a different
    column. Untick **First row contains headers** if your file starts with data rather than column names.
 7. Review the preview and the number of identifiers detected, then click **Create Segment**.
 
 ![Creating a segment from a CSV list](/img/cohort-synchronisation/csv-create-segment.png)
 
+:::warning Choose the environment carefully
+
+The identities you upload are only targeted in the environment you select, and that choice cannot be changed later. To
+target the same list in another environment, create a second segment there and upload the same file.
+
+:::
+
 ## Updating the members
 
 Membership only changes when you upload a new file, so re-upload whenever your list has moved on.

docs/docs/third-party-integrations/cohort-synchronisation/index.md

@@ -21,6 +21,14 @@ Cohort synchronisation is available on paid plans.
 
 :::
 
+:::warning Synchronised segments belong to one environment
+
+You choose the environment when you set the segment up, and it cannot be changed afterwards. The segment has no members
+in any other environment, so an override you add in, say, Production will not match anyone if the segment was
+synchronised into Development. To target the same group in another environment, set the segment up again there.
+
+:::
+
 ## Supported sources
 
 - [CSV import](/third-party-integrations/cohort-synchronisation/csv-import)