Change metacpan_web_local.yml instructions

The old instructions are not valid YAML.

Author: ehuelsmann

README.md

@@ -106,7 +106,7 @@ used can be changed in the `metacpan_web.conf` file. Ideally you would create a
 new file called `metacpan_web_local.conf` that contains
 
 ```bash
-api                 http://127.0.0.1:5000
+api: http://127.0.0.1:5000
 ```
 
 which will be loaded on top of the existing config file.