Fix hook_ranking() example in node.api.php

This issue has novice tasks. If you are an experienced core developer and have multiple commit mentions, please review novices' work on these tasks rather than doing them yourself. Feedback from experienced contributors is valued.

Problem/Motivation

The example code for hook_ranking() in node.api.php is incorrect.

        'arguments' => array(\Drupal::config('vote.settings').get('score_max')),

We're not concatenating the result of Drupal::config() with the result of get() here :). Should be Drupal::config()->get()

Proposed resolution

Fix code.

Remaining tasks

• Write patch (novice) Completed. Awaiting Review
• Review patch to check it fixes the issue, the change is properly documented and for coding standards. Provide test evidence (novice)
• Keep issue summary up to date (novice)

User interface changes

API changes