Fix faq: use yaml

[lucasvo]

I would like to use the tinlake FAQ feature we had on the website for this going forward. See this for the implementation: https://github.com/centrifuge/website/pull/179/files#diff-ec5978fa5620c8847e98a432f6e95a9602a218b6f5e0f66e75a07663ba6b8bbfR1

This addresses my comment in #236

[sounak98]

@lucasvo currently we are just using the same layout as any other document page, so I have updated the FAQ as an md file. If we need to get it from yaml, we will need a design and will have to render the raw data from yaml.

Personally I feel there there is not much difference in a md and a yaml file from the perspective of non tech people having to update it, but if you want it as a yaml, @Dy-Dedi could you ask Catarina to design a very basic FAQ page?