move the how-to-do-a meetup document from hardfire/developers-nepal to here

[hardfire]

[geshan]

any description on how to do it?

[hardfire]

I had a small documentation here (https://github.com/hardfire/developers-nepal/wiki) on how to organize a meetup and we should document this as well. Will be helpful for someone who wants to organize. moving forward we can also have a list of friendly venues that we can reach out to in case its hard to find one. Just a thought.