Changed param type for token from string to env_var_name (#24)

Author: pbaderia01

orb.yml

@@ -20,9 +20,9 @@ commands:
         type: string
         default: ""
       token:
-        description: Set the private repository token (defaults to environment variable $CODECOV_TOKEN)
-        type: string
-        default: ${CODECOV_TOKEN}
+        description: Set the private repository token as the value of the variable CODECOV_TOKEN using CircleCI Environment Variables.
+        type: env_var_name
+        default: CODECOV_TOKEN
       upload_name:
         description: Custom defined name of the upload. Visible in Codecov UI
         type: string