Merge pull request #187 from whj4674672/master

[add] uf2tool

Author: Guozhanxin

projects/uf2_boot/tools/uf2tool2.exe

@@ -0,0 +1,6 @@
+<?xml version="1.0" encoding="utf-8" ?>
+<configuration>
+    <startup> 
+        <supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.6.1" />
+    </startup>
+</configuration>