devapp/owners: add {index,sum,proxy}.golang.org to owners

This change adds {index,sum,proxy}.golang.org to the list of Go
resources the Go team owns since we occasionally see issues related to
these domains appear on the issue tracker.

This change adds heschi, hyangah, and katie as primary owners and
findleyr as a secondary owner.

Change-Id: I375e6b9ec6d627a7b9c2a1687d6d1ab7097194d0
Reviewed-on: https://go-review.googlesource.com/c/build/+/322552
Trust: Michael Knyszek <mknyszek@google.com>
Trust: Katie Hockman <katie@golang.org>
Run-TryBot: Michael Knyszek <mknyszek@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Robert Findley <rfindley@google.com>
Reviewed-by: Katie Hockman <katie@golang.org>
Reviewed-by: Heschi Kreinick <heschi@google.com>
diff --git a/devapp/owners/table.go b/devapp/owners/table.go
index 584816b..5a602b5 100644
--- a/devapp/owners/table.go
+++ b/devapp/owners/table.go
@@ -872,8 +872,16 @@
 	"go.dev": {
 		Primary: []Owner{pearring},
 	},
+	"index.golang.org": modProxyOwners,
+	"proxy.golang.org": modProxyOwners,
+	"sum.golang.org":   modProxyOwners,
 }
 
 var wasmOwners = &Entry{
 	Primary: []Owner{neelance, cherryyz},
 }
+
+var modProxyOwners = &Entry{
+	Primary:   []Owner{katie, heschi, hyangah},
+	Secondary: []Owner{findleyr},
+}