documentation docs gplv3 markdown-language gpl3 markdown-lang blueberryos blueberryos-project blueberryos-development blueberryos-operating-system-project blackberryos-alternative blackberry-alternative blueberryos-docs blueberryos-documentation blueberryos-apps-calculator blueberryos-calculator-app blueberryos-calculator-app-project blueberryos-calculator-app-development blueberryos-calculator-app-docs blueberryos-calculator-app-documentation