owners: add owners for io and strings packages

Change-Id: I388a2404eeb14591c86452c4c64e401691ee384e
Reviewed-on: https://go-review.googlesource.com/c/build/+/188377
Reviewed-by: Robert Griesemer <gri@golang.org>
diff --git a/devapp/owners/table.go b/devapp/owners/table.go
index 7b41bfa..acc5393 100644
--- a/devapp/owners/table.go
+++ b/devapp/owners/table.go
@@ -370,6 +370,10 @@
 		Primary:   []Owner{bradfitz, iant},
 		Secondary: []Owner{josharian},
 	},
+	"go/src/io": {
+		Primary:   []Owner{gri},
+		Secondary: []Owner{iant, bradfitz},
+	},
 	"go/src/log": {
 		Primary: []Owner{r},
 	},
@@ -513,6 +517,10 @@
 	"go/src/strconv": {
 		Primary: []Owner{rsc, gri, iant, bradfitz},
 	},
+	"go/src/strings": {
+		Primary:   []Owner{gri},
+		Secondary: []Owner{iant, bradfitz},
+	},
 	"go/src/sync": {
 		Primary: []Owner{rsc, iant, dvyukov, austin},
 	},