message: Update readme
  Include raspberrypi3 folder in readme description
diff: @@ -8,6 +8,7 @@ This folder contains the user guides, helper documents, doxygen documents, etc.
  | --------- | ----------- |
  | dragonboard410c | Instructions to build and use all necessary software on Dragonboard 410c |
  | linux | Instructions to build and use all necessary software on a Linux host |
  +| raspberrypi3 | Instructions to build and use all necessary software on Rasbpberry PI 3 |
  | windows | Instructions to build and use all necessary software on a Windows host |
  | img | Images used in various documentation files |
  | CMakeLists.txt | Rules for generating the doxygen documentation on request |
  