Update reference/runtime-environment.html.md

Co-authored-by: catflydotio <[email protected]>

reference/runtime-environment.html.md

@@ -36,7 +36,7 @@ Not to be confused with the [HTTP header](/docs/reference/runtime-environment/#f
 **Machine ID**: The unique ID that flyctl commands and the Machines API use to identify a Machine. You'll also see it in the [logs](/docs/flyctl/logs/).
 
 ### `FLY_MACHINE_VERSION`
-**Machine Configuration Version**: Every Machine configuration has an associated version. Whenever you update a Machine's configuration (including when you update its Docker image), it gets a new `FLY_MACHINE_VERSION`. The exception to this is that changing only the Machine's metadata doesn't trigger a new version.
+**Machine Configuration Version**: Any update to a Machine's configuration, including its Docker image, generates a new `FLY_MACHINE_VERSION`. Updating metadata alone does not trigger a new version. `FLY_MACHINE_VERSION` has the same value as `Instance ID` in the output of `fly machine status`. 
 
 ### `FLY_PRIVATE_IP`
 **Private IPv6 Address**: The IPv6 address of the Machine on its [6PN private network](/docs/reference/private-networking/).