Adds missing command for install (mac) (#90)

* Adds missing command for install (mac)

Required for users who didn't previously have Rust installed.

* minor wording change

Co-authored-by: Jong Wook Kim <jongwook@nyu.edu>

README.md

@@ -40,7 +40,7 @@ choco install ffmpeg
 scoop install ffmpeg
 ```
 
-You may need [`rust`](http://rust-lang.org) installed as well, in case [tokenizers](https://pypi.org/project/tokenizers/) does not provide a pre-built wheel for your platform. If you see installation errors during the `pip install` command above, please follow the [Getting started page](https://www.rust-lang.org/learn/get-started) to install Rust development environment.
+You may need [`rust`](http://rust-lang.org) installed as well, in case [tokenizers](https://pypi.org/project/tokenizers/) does not provide a pre-built wheel for your platform. If you see installation errors during the `pip install` command above, please follow the [Getting started page](https://www.rust-lang.org/learn/get-started) to install Rust development environment. Additionally, you may need to configure the `PATH` environment variable, e.g. `export PATH="$HOME/.cargo/bin:$PATH"`.
 
 
 ## Available models and languages