Update CODEOWNERS for managing subscriptions

@skermajo and I have discussed that this page better fits BIT over PGT so I've updated the code owners.

.github/CODEOWNERS

@@ -39,9 +39,9 @@
 
 /docs/getting-started/first-runbook-run/ @OctopusDeploy/team-product-growth
 
-# updates to the managing octopus subscriptions page are reviewed by team-product-growth
+# updates to the managing octopus subscriptions page are reviewed by team-billing-experience
 
-/docs/getting-started/managing-octopus-subscriptions.md @OctopusDeploy/team-product-growth
+/docs/getting-started/managing-octopus-subscriptions.md @OctopusDeploy/team-billing-experience
 
 # updates to the samples instance page are reviewed by team-solutions