Fix link URL to CSV schema files in README.md

Author: J. Manrique Lopez de la Fuente

README.md

@@ -177,7 +177,7 @@ Data model
 Each of the indexes are based on a previous definition. This
 is declared in CSV format with two columns: name and type.
 
-More information at the [Schema README](schema/README.md) file.
+More information at the [Schema](https://github.com/chaoss/grimoirelab-elk/tree/master/schema) directory.
 
 
 How this info was retrieved