Remove 3rd party store URLs from the SRD

[Gulluth]

Vov 1-3 and the DE are out of print and largely unavailable. The two exceptions for the zines availability are Leo's store Antipode, and Lulu for print on demand. Since maintaining these links for future releases of the zine will result in whack-a-mole with 3rd party eCommerce platforms, I am opting to remove the 3rd party links entirely while maintaining links to Leo's store and Lulu.

This affects README.md and translations (vaarn-ko).