Move the notes key-value from meta.json to it's own (markdown) file

[ishan-appendix]

Currently the notes for the datasets reside inside the meta.json which can only be viewed via the databank platform (i.e https://databank.watchdog.team/dataset/ministry-of-health-institutions). The problem with this approach is that the notes will not be visible through any other mediums for the people who really need to access it. Generally it would make sense to have the notes in it's own markdown (or similar) file so that there won't be any reliance on the databank platform to read the file.