Add missing prompt in README example

fnichol · fnichol · commit 5b6a05346518 · 2019-10-10T12:10:53.000-06:00
Signed-off-by: Fletcher Nichol &lt;fnichol@nichol.ca&gt;
diff --git a/README.md b/README.md
@@ -57,7 +57,7 @@ If [Rust](https://rustup.rs/) is installed, then installing with Cargo is
 straight forward:
 
 ```console
-cargo install iocage-provision
+$ cargo install iocage-provision
 ```
 
 ### From Source
