message: Add link to building guide
diff: @@ -3,7 +3,7 @@ Thank you for submitting a PR!
  Please delete this standard text once you've created your own description.
  If you make changes to any of the code generators (`src/idl_gen*`) be sure to
  -build your project, as it will generate code based on the changes. If necessary
  +[build](https://google.github.io/flatbuffers/flatbuffers_guide_building.html) your project, as it will generate code based on the changes. If necessary
  the code generation script can be directly run (`scripts/generate_code.py`),
  requires Python3. This allows us to better see the effect of the PR.
  