Content revision: Promotion page

[vcarl]

Break up promotion to more clearly address different audiences who want to promote different types of materials:

• Recruiters
• OSS maintainers (and would-be maintainers)
• Content creators and coaches
• Entrepreneurs
• Conference organizers
• Hackathons and event organizers

[vcarl]

Should have a conferences page that has a contact method for "renting" the community space for conference attendees, and another for how best to share CFP announcements

[vcarl]

Made some progress in https://github.com/nodeiflux/documents/blob/main/promotion.md