Add details on the toolchain_type
Closes
@@ -128,6 +128,8 @@ lazy loading of toolchains.
Below is an example toolchain definition:
```python
+toolchain_type(name = 'my_toolchain_type')
+
toolchain(
name = 'linux_toolchain',
toolchain_type = '//path/to:my_toolchain_type',
