add a readme section about version compatibility

README.md

@@ -81,6 +81,27 @@ The `scipy-stubs` package is available as on PyPI:
 pip install scipy-stubs
 ```
 
+## Version Compatibility
+
+### Type-checkers
+
+For validation and testing, `scipy-stubs` primarily uses
+[`basedmypy`](https://github.com/KotlinIsland/basedmypy) (a `mypy` fork) and
+[`basedpyright`](https://github.com/DetachHead/basedpyright) (a `pyright` fork).
+Because they are in generally stricter than `mypy` and `pyright`, they should be
+compatible as well.
+If you find that this is not the case, then don't hesitate to open an issue.
+
+### Required dependencies
+
+The versioning scheme of `scipy-stubs` includes the compatible `scipy` version.
+Later versions might work too, but in case of API-changes, the stubs could be outdated.
+
+Apart from `scipy`'s own dependencies (e.g. `numpy`), the only other
+required dependency is [`optype`](https://github.com/jorenham/optype).
+
+The exact version requirements are specified in the [`pyproject.toml`](pyproject.toml).
+
 ## Development Progress
 
 | Package or module                 | Stubs status    |