Update README.md

Author: kiddin9

README.md

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 A new Luci theme for LEDE/OpenWRT  
 Edge is a clean HTML5 theme for LuCI. It is based on luci-theme-argon Template  
 
+Master branch adapt to official mainline snapshot.
 Luci 18.06: https://github.com/garypang13/luci-theme-edge/tree/18.06
 
 ## Thanks to