Update book links to sway-lib-core in Section 3.2
# Libraries
-Libraries in Sway are files used to define new common behavior. An example of this is the [Sway Core Library](https://github.com/FuelLabs/sway-lib-core) which outlines various methods that the `u64` type implements.
+Libraries in Sway are files used to define new common behavior. An example of this is the [Sway Core Library](https://github.com/FuelLabs/sway/tree/master/sway-lib-core) which outlines various methods that the `u64` type implements.
## Writing Libraries
@@ -10,7 +10,7 @@ Libraries are denoted using the `library` keyword at the beginning of the file,
library my_library;
```
-A good reference library to use when learning library design is the [Sway Core Library](https://github.com/FuelLabs/sway-lib-core). The `add` function interface is defined via the `Add` trait and then implemented for `u64`. This attaches this `add` function to the type so that, when the trait is imported, `u64`s can utilize the `add` function.
+A good reference library to use when learning library design is the [Sway Core Library](https://github.com/FuelLabs/sway/tree/master/sway-lib-core). The `add` function interface is defined via the `Add` trait and then implemented for `u64`. This attaches this `add` function to the type so that, when the trait is imported, `u64`s can utilize the `add` function.
```sway
pub trait Add {
