lib:fix grammar error and make it clearer for comments

1) Should be passive voice instead of `can overridden`.
2) Change the order of the two sentences to make it more clear about
'What can be overridden' instead of 'Can be overridden'.

PR-URL: nodejs#23799
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>

lib/repl.js

@@ -126,8 +126,9 @@ function hasOwnProperty(obj, prop) {
   return Object.prototype.hasOwnProperty.call(obj, prop);
 }
 
-// Can overridden with custom print functions, such as `probe` or `eyes.js`.
-// This is the default "writer" value if none is passed in the REPL options.
+// This is the default "writer" value, if none is passed in the REPL options,
+// and it can be overridden by custom print functions, such as `probe` or
+// `eyes.js`.
 const writer = exports.writer = (obj) => util.inspect(obj, writer.options);
 writer.options = Object.assign({},
                                util.inspect.defaultOptions,