Lesson 6 improvements and some refactoring

[tdeknecht]

fix: lesson-6 now only related to bringing it all together. Added better docs and refactored some code refactor: lesson-5 had some poorly named functions. Renamed them and added better comments refactor: lesson-7 is now for the OLED module and can be considered a bonus lesson

[tdeknecht]

Related to issue https://github.com/StateFarm-STEM/hablogger/pull/58