Update roadmap

docs/roadmap.txt

@@ -2,5 +2,9 @@
 Roadmap
 =======
 
-Setuptools is primarily in maintenance mode. The project attempts to address
-user issues, concerns, and feature requests in a timely fashion.
+Setuptools has the following large-scale goals on the roadmap:
+
+- Harmonize declarative config with pyproject.toml syntax.
+- Deprecate and remove setup_requires and easy_install in
+  favor of PEP 518 build requirements and pip install.
+- Adopt the Distutils package and stop monkeypatching stdlib.