Add MSRV Policy

README.md

@@ -160,6 +160,21 @@ This uses the Windows AFD system to access socket readiness events.
 [issue #1152]: https://github.com/tokio-rs/mio/issues/1152
 [issue #1444]: https://github.com/tokio-rs/mio/issues/1444
 
+## MSRV Policy
+
+The MSRV (Minimum Supported Rust Version) is fixed for a given minor (1.x)
+version. However it can be increased when bumping minor versions, i.e. going
+from 1.0 to 1.1 allows us to increase the MSRV. Users unable to increase their
+Rust version can an older minor version instead. Below is a list of Mio versions
+and their MSRV:
+
+ * v0.8: Rust 1.46.
+ * v1.0: Rust 1.74.
+
+Note however that Mio also has dependencies, which might have different MSRV
+policies. We try to tick to the above policy when updating dependencies, but
+this is not always possible.
+
 ## Unsupported flags
 
 Mio uses different implementations to support the same functionality depending