Add methodology section

Author: ezzatron

README.md

@@ -534,6 +534,26 @@ const s_xt = -Math.asin(dot(c_E, n_EB_E)) * r_Earth;
 const d_xt = -dot(c_E, n_EB_E) * r_Earth;
 ```
 
+## Methodology
+
+If you look at the test suite for this library, you'll see that there are very
+few concrete test cases. Instead, this library uses model-based testing, powered
+by [fast-check], and using the [Python nvector library] as the "model", or
+reference implementation.
+
+[fast-check]: https://fast-check.dev/
+[python nvector library]: https://nvector.readthedocs.io/
+
+In other words, this library is tested by generating large amounts of "random"
+inputs, and then comparing the output with the Python library. This allowed me
+to quickly port the library with a high degree of confidence in its correctness,
+without a deep understanding of the underlying mathematics.
+
+If you find any issues with the implementations, there's a good chance that the
+issue will also be present in the Python library, and an equally good chance
+that I won't personally understand how to fix it 😅 Still, don't let that stop
+you from opening an issue or a pull request!
+
 ## References
 
 - Gade, K. (2010). [A Non-singular Horizontal Position Representation], The