governance: Guidelines for applying for content rewards

[mochet]

WIP, this is needed to give new users an idea of how to best approach the council. Most of the work done in this area has been about coding and other work, but for video/content production it would be good to have a distinct set of guidelines for new users that can be built and improved upon over time.

This will also help to build a range of content that is funded by Joystream post-mainnet.