README: Compatible meters google sheets link.

README.md

@@ -68,6 +68,8 @@ Currently the only tested meter is the Itron C1SR and Itron 40G. However, the pr
 
 Check out the table of meters I've been compiling from various internet sources: [ERT Compatible Meters](https://github.com/bemasher/rtlamr/blob/master/meters.md)
 
+User provided, but otherwise unverified compatible meters: [Google Sheets](https://docs.google.com/spreadsheets/d/1lTeHkk7rwFfq0joMWngrhnJA2nXAk4m82eApVaAKfhw/edit?usp=sharing)
+
 Look for an FCC ID label on your meter, it should identify the two-digit commodity or endpoint type and the eight- or ten-digit endpoint ID of your meter: `## ########[##]`. Below are a few examples:
 
 ![Example FCC Label (1)](assets/fcc_label_01.png)