docs(README.md): add notice about maintainence status

Author: jedwards1211

README.md

@@ -7,6 +7,26 @@ A runtime type system for JavaScript with full [Flow](https://flowtype.org/) com
 
 ---
 
+## Maintenance Status
+
+This project is not very well maintained anymore due to its complexity and maintainers' burnout with Flow in general.
+
+### Statement from @jedwards1211
+
+At the moment I need to keep this working in some production projects that use it for API input validation
+(using the `optInOnly` option instead of blanket runtime validation everywhere).
+
+However, I would like to eventually migrate those projects to either:
+- a library where I declare validators that I can extract value types from.  I created [`typescript-validators`](https://github.com/jcoreio/typescript-validators)
+  for this purpose in TypeScript
+- a very pared-down version of `babel-plugin-flow-runtime` that generates validators where requested from Flow type annotations,
+  but only supports certain types and doesn't automatically inject runtime validation everywhere.
+
+If I had the time I would even migrate my production projects to TypeScript though, so I'm not sure I'll continue to use
+Flow and `flow-runtime` heavily in the long term.
+
+## Contributing
+
 This is a [lerna](https://github.com/lerna/lerna) powered mono-repo, composed of the following projects:
 
   - [flow-runtime](./packages/flow-runtime): The core runtime type system.
@@ -16,7 +36,7 @@ This is a [lerna](https://github.com/lerna/lerna) powered mono-repo, composed of
   - [flow-runtime-mobx](./packages/flow-runtime-mobx): Adds mobx support to flow-runtime.
   - [flow-runtime-docs](./packages/flow-runtime-docs): React powered documentation site.
 
-## Contributing
+### Getting started
 
 First clone the repo: