README: Unix: Describe pycopy-dev variant.
@@ -163,6 +163,14 @@ Browse available modules on [PyPI](https://pypi.org/search/?q=pycopy-).
Standard library modules come from
[pycopy-lib](https://github.com/pfalcon/pycopy-lib) project.
+`pycopy` executable built following the instructions above is a
+"production" executable for native Pycopy software. It's also possible
+to build `pycop-dev` executable which provides additional reflection,
+diagnostics, and extensibility capabilities, at the expense of code
+size and memory usage efficiency. In particular, `pycopy-dev` is more
+compatible with software written for CPython. To build the `pycopy-dev`
+variant, run `make dev`.
+
External dependencies
---------------------
