Really there should be no copyright symbol at all since it is an open source project. No one holds exclusive copyright (i.e. the right to copy). Any of us can go to github and legally create a copy in seconds. It's not a thing.

What this should look like is the liner notes to an album. Here's the partial liner notes to Thriller as an example.

Brian Banks – keyboards, synthesizer (track 4), synthesizer programming (2) Michael Boddicker – keyboards, synthesizers (tracks 1–2), Emulator (6–9), Vocoder (8) N'dugu Chancler – drums (tracks 2, 6, 8) Paulinho da Costa – percussion (tracks 1, 7) David Foster – synthesizers, synthesizer arrangements on "The Girl is Mine" Gary Grant – trumpet, flugelhorn (tracks 1–2, 4) Eddie Van Halen – guitar solo on "Beat It" Jerry Hey – trumpet (tracks 1–2, 4), flugelhorn (1–2, 4), horn arrangements (1–2, 4), string arrangements (3, 6), strings conductor (3) Michael Jackson – co-producer (All tracks), lead vocals (All tracks), drum case beater (track 5), bathroom stomp board (1), background vocals (1, 4–6), handclaps (8), vocal arrangements (1, 3, 5–6), rhythm arrangements (1, 5–6), horn arrangements (1), synthesizer arrangements (6) Paul Jackson, Jr. – guitar (tracks 5, 8–9) Louis Johnson – bass guitar (tracks 1, 3, 6, 8–9) Quincy Jones – producer (All tracks), rhythm arrangements (tracks 1, 3, 5), vocal arrangements (3), musical arrangements (8) Steve Lukather – guitar (tracks 3, 5, 7), bass guitar (5), musical arrangements (7) Anthony Marinelli – synthesizer programming (tracks 2, 4) Paul McCartney – vocals on "The Girl Is Mine"

Not sure exactly how that would look in this case, but it would be cool.