Update stella link
Update stella link

stella is on GitHub, changed link to reflect that
DirtyHairy/6502.ts,6502ts/6502.ts,DirtyHairy/6502.ts,6502ts/6502.ts,DirtyHairy/6502.ts,6502ts/6502.ts,6502ts/6502.ts,DirtyHairy/6502.ts,6502ts/6502.ts