remove reference to specific Rust version

Closes #6.

Author: euclio

README.md

@@ -13,9 +13,8 @@ This plugin should be considered alpha-quality software.
 
 vim-markdown-composer requires [Python 3], [Rust], [cargo], and [Neovim].
 
-vim-markdown-composer officially targets the latest version of stable Rust.
-However, it should work in versions as early as 1.3. If you'd like to install
-multiple versions of Rust on the same machine, check out
+vim-markdown-composer officially targets the latest version of [stable Rust]. If
+you'd like to install multiple versions of Rust on the same machine, check out
 [multirust](https://github.com/brson/multirust).
 
 If you haven't already installed the Python 3 plugin host, install it with `pip3
@@ -74,4 +73,4 @@ previews.
 [vim-plug]: https://github.com/junegunn/vim-plug
 [msgpack-rpc]: https://github.com/msgpack-rpc/msgpack-rpc
 [aurelius]: https://github.com/euclio/aurelius
-
+[stable Rust]: https://www.rust-lang.org/downloads.html