Add library RUI3-Arduino-Library

[beegee-tokyo]

RAKWireless library for communication over UART with RUI3 based WisDuo modules.

[github-actions]

Arduino Lint has suggestions for possible improvements to https://github.com/beegee-tokyo/RUI3-Arduino-Library:

Linting library in RUI3-Arduino-Library
INFO: No header file found matching library name (RUI3-Arduino-Library.h). Best practices are for primary header        
      filename to match library name.                                                                                   
      See: https://arduino.github.io/arduino-cli/latest/library-specification/#libraryproperties-file-format            
      (Rule LS008)                                                                                                      
WARNING: library.properties name value RUI3-Arduino-Library is longer than the recommended length of 16 characters.
         See: https://arduino.github.io/arduino-cli/latest/library-specification/#libraryproperties-file-format    
         (Rule LP010)                                                                                              
WARNING: Library name RUI3-Arduino-Library contains "Arduino". This is superfluous.                            
         See: https://arduino.github.io/arduino-cli/latest/library-specification/#libraryproperties-file-format
         (Rule LP014)                                                                                          
WARNING: Library name RUI3-Arduino-Library contains "library". This is superfluous.                            
         See: https://arduino.github.io/arduino-cli/latest/library-specification/#libraryproperties-file-format
         (Rule LP016)                                                                                          
WARNING: Invalid category field value IO in library.properties                                                 
         See: https://arduino.github.io/arduino-cli/latest/library-specification/#libraryproperties-file-format
         (Rule LP038)                                                                                          
WARNING: Unable to load the library.properties url field: 404 Not Found                                        
         See: https://arduino.github.io/arduino-cli/latest/library-specification/#libraryproperties-file-format
         (Rule LP042)                                                                                          

Linter results for project: 0 ERRORS, 5 WARNINGS

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Linting sketch in RUI3-Arduino-Library/examples/RUI3-AT-ABP

Linter results for project: no errors or warnings

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Linting sketch in RUI3-Arduino-Library/examples/RUI3-AT-OTAA

Linter results for project: no errors or warnings

-------------------

Linter results for projects: 0 ERRORS, 5 WARNINGS

[github-actions]

Your submission has now been accepted! Thanks for your contribution to the Arduino Library Manager index.

The library(s) will be available for installation via Library Manager within a day's time.

You can check the logs from the Library Manager indexer for your library(s) here:
http://downloads.arduino.cc/libraries/logs/github.com/beegee-tokyo/RUI3-Arduino-Library/