Remove broken link (GR-9548)

tools/README.md

@@ -13,7 +13,7 @@ language launchers. Some tools have their [APIs](http://graalvm.github.io/graal/
 
 ## Setup and Build
 
-Graal uses [MX build tool](https://github.com/graalvm/mx/), which must be downloaded
+Graal uses the [MX build tool](https://github.com/graalvm/mx/), which must be downloaded
 and put onto your PATH. Also, point `JAVA_HOME` to a
 [labsjdk](http://www.oracle.com/technetwork/oracle-labs/program-languages/downloads/index.html).
 
@@ -44,7 +44,6 @@ list. To contribute a change, verify it using
 $ mx gate
 ```
 and start a [pull request](https://help.github.com/articles/using-pull-requests/).
-Detailed info can be found in the [contributing document](CONTRIBUTING.md).
 
 ## License