Update docs for request forwarding GA (#140)

Author: lafentres

website/docs/cloud-docs/agents/request-forwarding.mdx

@@ -59,7 +59,7 @@ If you want to use a private VCS provider, you must configure your HCP Terraform
 
 ## Requirements and Limitations
 
-Agent version 1.15.0+ is required to use request forwarding.
+Agent version 1.21.1+ is required to use request forwarding.
 
 We recommend that you allocate at least 250MB of additional system memory specifically
 for request forwarding. This is in addition to the minimum