Make license formatting match GitHub's reference text

[per1234]

GitHub uses the licensee ruby gem to detect the license type of the repository. licensee uses the license texts from choosealicense.com so if the text of your license file differs from their license it will not be recognized. GitHub allows filtering searches by license type and also shows the license type on the homepage of your repository and when viewing the license page but these features are only available when the license is recognized.

This does NOT change the actual content of the license in any way.

[gyssels]

@per1234 I will accept PR on gyssels/Arduino-CmdMessenger, and I messaging the other PR submitters so it can become an active branch I engage myself to do a full PR back here if in the future I'll not maintain this anymore.