DOCS-2452: clarification about millis field in query analysis

Author: Sam Kleinman

source/reference/database-profiler.txt

@@ -256,8 +256,9 @@ operation.
 
 .. data:: system.profile.millis
 
-   The time in milliseconds for the server to perform the operation.
-   This time does not include network time reading nor sending data.
+   The time in milliseconds from the perspective of the
+   :program:`mongod` from the beginning of the operation to the end of
+   the operation.
 
 .. data:: system.profile.client