Fix Sway Quickstart link in the Sway Book
- [Introduction](./introduction/index.md)
- [Installation](./introduction/installation.md)
- - [Sway Quickstart](./introduction/overview.md)
+ - [Sway Quickstart](./introduction/sway_quickstart.md)
- [The Fuel Toolchain](./introduction/fuel-toolchain.md)
- [A Forc Project](./introduction/forc_project.md)
- [Standard Library](./introduction/standard_library.md)
