chore(libcontainer): small grammar fix in types_test

Someone probably got really used to typing er on the end of contain :)

Docker-DCO-1.1-Signed-off-by: Brandon Philips <brandon.philips@coreos.com> (github: philips)
Upstream-commit: ad7e7d612390d09d3a54fd82dda9687deb3b0cbe
Component: engine

components/engine/pkg/libcontainer/types_test.go

@@ -30,6 +30,6 @@ func TestCapabilitiesContains(t *testing.T) {
 		t.Fatal("capabilities should not contain SYS_ADMIN")
 	}
 	if !caps.Contains("MKNOD") {
-		t.Fatal("capabilities should container MKNOD but does not")
+		t.Fatal("capabilities should contain MKNOD but does not")
 	}
 }