Rename usermod EXAMPLE_v2 to EXAMPLE

It'd be better to not propagate the 'v2' suffix any further.  This is
the standard flavor of usermods now.

usermods/EXAMPLE/library.json

@@ -0,0 +1,4 @@
+{
+  "name:": "EXAMPLE",
+  "dependencies": {}
+}

usermods/EXAMPLE/readme.md

@@ -4,7 +4,6 @@ In this usermod file you can find the documentation on how to take advantage of
 
 ## Installation 
 
-Copy `usermod_v2_example.h` to the wled00 directory.  
+Add `EXAMPLE` to `custom_usermods` in your PlatformIO environment and compile!
-Uncomment the corresponding lines in `usermods_list.cpp` and compile!  
 _(You shouldn't need to actually install this, it does nothing useful)_
 

usermods/EXAMPLE/usermod_v2_example.cpp

@@ -1,5 +1,3 @@
-#pragma once
-
 #include "wled.h"
 
 /*
@@ -404,3 +402,6 @@ void MyExampleUsermod::publishMqtt(const char* state, bool retain)
   }
 #endif
 }
+
+static MyExampleUsermod example_usermod;
+REGISTER_USERMOD(example_usermod);