Move metadata about Authors, Raags(, Nitnem?) to Markdown

[bogas04]

I feel that keeping those docs in Markdown can serve a lot of things:

• Easy formatting for collaborators who would love to write text.
• The markdown files can be used in open source world too.
• Links (Katha Kirtan for Nitnem?), images etc can be added without editing codebase.
• Makes more sense for having a markdown parser that contributes to 6.2% of bundle size #95 :dancing_men:
• Later we can add more docs similarly.

[bogas04]

Surgyan has nice details of several raags (avroh aaroh, with bandish coming soon). We can add it until some Sikh veerji/pbhenji does the same for Gurbani Raags

[bogas04]

Moved descriptions of Raags and Authors to markdown files now.

Updated README descriptions as well to accept contributions.