readme: require Rust 1.37.0, because enum aliases need it

Author: axic

CHANGELOG.md

@@ -18,14 +18,14 @@ and this project adheres to [Semantic Versioning].
 
 ### Changed
 
+- Require Rust 1.37.0 as a minimum.
 - In the Rust bindings mark read-only functions in `ExecutionContext` as non-mutating.
   [#444](https://github.com/ethereum/evmc/pull/444)
 - In the C++ `HostInterface` the logically read-only methods are marked with `const`.
   [#461](https://github.com/ethereum/evmc/pull/461)
 - Updated dependencies of the Rust bindings to latest stable versions.
   [#462](https://github.com/ethereum/evmc/pull/462)
 
-
 ## [7.0.0] „Istanbul Ready” — 2019-11-11
 
 This version of EVMC delivers compatibility with Istanbul EVM revision.

README.md

@@ -24,7 +24,7 @@ Please visit the [documentation].
 | **C**                         | C99, C11              | GCC 6+, clang 3.8+, MSVC 2015+
 | **C++**                       | C++11, C++14, C++17   | GCC 6+, clang 3.8+, MSVC 2015+
 | **Go** _(bindings)_           | 1.9 - 1.12            |
-| **Rust** _(bindings)_[¹](#n1) | 2018 edition          | 1.31.0 and newer
+| **Rust** _(bindings)_[¹](#n1) | 2018 edition          | 1.37.0 and newer
 
 <b id="n1">1</b>. Rust support is limited and not complete yet, but it is mostly functional already. Breaking changes are possible at this stage.