Create separate docs for coordination timelines

[mxie]

Most of the roles have been taken care of already but there are still the following:

• catering
• sponsorships
• MC

Basically, we should remove their corresponding parts of the timeline in the repo README.md and then put them in their own files (e.g. mc.md) or in new READMEs located in a new folder named after the role (e.g. registration/README.md).