Update CG-08-13.md

[tlively]

[tlively]

cc @guybedford and @alexcrichton for slides links

[guybedford]

Slides available at https://docs.google.com/presentation/d/1Po0FlImrq1DJUARuZRssDshVtQGwz-YlnsdVrkA2UvE.

[alexcrichton]

Mine are at https://docs.google.com/presentation/d/1szj9D2q43NrQhxtys2OBAAMjeAOanCNMIS4D0gPaYuI

[alexcrichton]

@tlively or @dschuff would y'all be able to set up a new proposal repo and give @jameysharp and I access?

[tlively]

Yep, I can take a stab at that.

[tlively]

https://github.com/WebAssembly/128-bit-arithmetic should be ready to go.

[alexcrichton]

Thanks!