docs(CONTRIBUTING): add a note for single test run
test-one.sh needs to run `dot` command which is installed via Graphviz.
Else, running the script throws error - `dot` command not found.
@@ -152,6 +152,9 @@ $ cargo test
### Testing a Single Header's Bindings Generation and Compiling its Bindings
+Note: You will to need to install [Graphviz](https://graphviz.org/) since that
+is a dependency for running `test-one.sh`.
+
Sometimes its useful to work with one test header from start (generating
bindings for it) to finish (compiling the bindings and running their layout
tests). This can be done with the `tests/test-one.sh` script. It supports fuzzy
