Update Feature requests

Feature-requests.md

@@ -30,4 +30,5 @@
 | 028 | open | low | Change permissions on password-containing preference file to 600 |
 | 029 | open | low | Switch waterfall on/off (do we already have that?) |
 | 030 | open | medium | Add transmit audio capability |
+| 031 | open | low | Add s-meter, option to [fix units](https://owenduffy.net/blog/?p=10613) |