[core] Set required yarn version (#12864)

* [core] Set required yarn version

Before 1.4.0 bin commands could not be found when executed from
a workspace. See yarnpkg/yarn#4848

* Revert "[core] Set required yarn version"

This reverts commit e6260e3.

Netlify uses 1.3.2 which has the same issue. This also limits
users not just contributors.

* [core] Add note about build prerequisites

* Update CONTRIBUTING.md

CONTRIBUTING.md

@@ -61,6 +61,11 @@ To update the component API documentation (auto generated from component PropTyp
 yarn docs:api
 ```
 
+### Building locally
+
+To use the provided build scripts with yarn you have to install `yarn@^1.4.0`.
+Depending on the package you want to build just run `yarn workspace @material-ui/PACKAGE build`.
+
 ### Coding style
 
 Please follow the coding style of the current code base. Material-UI uses eslint, so if possible, enable linting in your editor to get real-time feedback. The linting rules are also run when Webpack recompiles your changes, and can be run manually with `yarn lint`.