change readme

Signed-off-by: pipiland2612 <[email protected]>

Author: pipiland2612

exp/README.md

@@ -1,7 +1,7 @@
 # client_golang experimental module
 
 Contains experimental utilities and APIs for Prometheus.
-The module may be contain breaking changes or be removed in the future.
+This code is used by released versions of Prometheus, but should not be relied upon outside the Prometheus project.
 
 Packages within this module are listed below.