add notes about what the db abstraction layers are and why they were chosen
add notes about what the db abstraction layers are and why they were chosen

CodeSelfStudy/codeselfstudy_flask,harli123/codeselfstudy_flask,harli123/codeselfstudy_flask,harli123/codeselfstudy_flask,CodeSelfStudy/codeselfstudy_flask,CodeSelfStudy/codeselfstudy_flask