[Folderly App] Manual deliverability best practices

Unfortunately, there are best practices that we cannot automatically check for one reason or another (in general or so far).

Therefore, we want to add manual best practices so that users are always aware of the best approaches in deliverability for any case.

Users will always be able to find out all important information about manual best practices without leaving the app and mark such practices as implemented.

Once a manual practice has been marked as completed, the user will always have the possibility to read the information related to this practice and, if necessary, mark it as not implemented.