update MSRV policy section

Author: newpavlov

README.md

@@ -53,10 +53,9 @@ The following describes the security level ratings associated with each hash fun
 
 See the [Security] page on Wikipedia for more information.
 
-### Minimum Supported Rust Version (MSRV)
+### Minimum Supported Rust Version (MSRV) Policy
 
-All crates in this repository support Rust 1.41 or higher.
-In future minimally supported version of Rust can be changed, but it will be done with a minor version bump.
+MSRV bumps are considered breaking changes and will be performed only with minor version bump.
 
 ## Usage