Update doc/contributing/pull-requests.md

Co-authored-by: Rich Trott <rtrott@gmail.com>

Author: bavulapati

doc/contributing/pull-requests.md

@@ -244,8 +244,9 @@ test suite. To run the tests (including code linting) on Unix / macOS:
 ./configure && make -j4 test
 ```
 
-We can speed up the builds by using Ninja. For more information, see the
-[Building Node.js with Ninja](building-node-with-ninja.md) document.
+We can speed up the builds by using [Ninja](https://ninja-build.org/). For more
+information, see
+[Building Node.js with Ninja](doc/contributing/building-node-with-ninja.md).
 
 And on Windows: