Remove nonprofit-specific language from default config

[crossthebridgetpa]

The default site description and SEO keywords reference "501(c)(3) nonprofit" but most meetup groups using this template are not incorporated nonprofits. The defaults should use "community" or "organization" instead.

Changes needed:

• config.ts default description: replace "501(c)(3) nonprofit" with "community"
• config.ts default SEO keywords: remove "nonprofit" keyword
• EIN field should be clearly optional/commented
• Any public-facing copy that says "nonprofit" should say "community" or "organization"

[crossthebridgetpa]

/opencode make a pr