Update snap installation document for stable release

Author: benfrancis

README.snap.md

@@ -5,7 +5,7 @@ A self-hosted web application for monitoring and controlling a building over the
 On Ubuntu Server/Ubuntu Desktop:
 
 ```
-$ sudo snap install --edge webthings-gateway
+$ sudo snap install webthings-gateway
 $ sudo snap connect webthings-gateway:system-observe
 $ sudo snap connect webthings-gateway:hardware-observe
 $ sudo snap connect webthings-gateway:network-manager
@@ -16,7 +16,7 @@ $ sudo snap restart webthings-gateway
 On Ubuntu Core:
 
 ```
-$ snap install --edge webthings-gateway
+$ snap install webthings-gateway
 $ snap install network-manager
 $ snap connect webthings-gateway:system-observe
 $ snap connect webthings-gateway:hardware-observe
@@ -36,5 +36,3 @@ To connect a USB dongle:
 `$ snap connect webthings-gateway:serial-port snapd:foo`
 
 (where "foo" is the name of the slot)
-
-Note: This snap package is currently experimental and may not yet be fully functional. For manual installation instructions of a stable version please see https://webthings.io/docs/gateway/installation/