Update lib/sourcebit.js

Author: eduardoboucas

lib/sourcebit.js

@@ -135,7 +135,7 @@ class Sourcebit {
 
             // If the option defines an `env` property and there's an environment variable defined with that name, we'll use
             // that as the default value. Otherwise, the default value will be the one defined by the `default` property, if
-            // one is defined.
+            // one is set.
             if (option.env && process.env[option.env] !== undefined) {
                 defaults[key] = process.env[option.env];
             } else if (option.default !== undefined) {