Add a note about the project status

Author: sourcefrog

README.md

@@ -35,6 +35,16 @@ From within a Rust source directory, just run
 cargo mutants
 ```
 
+## Project status
+
+As of April 2023 this is an actively-maintained spare time project. It is very usable as it is
+and there is room for future improvements, especially in adding new types of mutation.
+
+I expect to make releases about every one or two months, depending on how much time and 
+energy I have available.
+
+Constructive feedback is welcome but there is absolutely no warranty or guarantee of support.
+
 ## Further reading
 
 **The main documentation is the user guide at <https://mutants.rs/>.**