examples/misc/01-power/README.txt: Note that this is Chrome-only for now.

examples/misc/01-power/README.txt

@@ -1 +1,4 @@
 This example code reports power status (plugged in, battery level, etc).
+
+Note that only Chrome-based browsers support this API currently. Firefox and
+Safari will report this as unsupported, but this may change later!