Add About page

[rolznz]

Tell people the awesome things they can do with this PoS

• It can be shared with employees without risk of loss of funds
• It works custodially or self-custodially
• Add github link

Like Bumi just created a PoS connected to NWC (Breez SDK) and paid it using NWC connected to his Umbrel. Fully self-custodial flow :boom:

[rolznz]

Done in https://github.com/getAlby/pos/commit/f86e2058344510256b918292227ae5f245c4b825