Update debug/dump cmd with Cluster-Environment-Name header (#2672)

This is needed since the dump includes the PlacmentSource

docs/troubleshooting/index.md

@@ -40,8 +40,14 @@ This endpoint can be used on both the db nodes as well as the coordinator/query
 
 To use this, simply run the following on either the M3DB debug listen port or the regular port on M3Coordinator.
 
+You may need to include the following headers:
+
+--8<--
+docs/common/headers_placement_namespace.md
+--8<--
+
 ```
-curl <m3db_or_m3coordinator_ip>:<port>/debug/dump > <tmp_zip_file.zip>
+curl -H "Cluster-Environment-Name: [set if not default]" <m3db_or_m3coordinator_ip>:<port>/debug/dump > <tmp_zip_file.zip>
 
 # unzip the file
 unzip <tmp_zip_file.zip>