Changed format of the boards files

boards/raspberry_pi3.md

-# Boards
-
-These boards were tested and the features are working:
-
-
-
-## Raspberry Pi 3
+# Raspberry Pi 3
 
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boards/raspberry_pi4.md

-# Boards
-
-These boards were tested and the features are working:
-
-
-## Raspberry Pi 4
+# Raspberry Pi 4
 
 Image :
 

boards/surface_pro2.md

-# Boards
-
-These boards were tested and the features are working:
-
-## Surface Pro2 
+# Surface Pro2 
 
 Image :
 

boards/up-squared.md

-# Boards
-
-These boards were tested and the features are working:
-
-
-
-## Up²
+# Up²
 
 Image :