disallowKeywordsOnNewLine: fix documentation format

Two of the examples had an extra space before the comment `*` which messes up the generated documentation.

Closes gh-2052

Author: dharkness

lib/rules/disallow-keywords-on-new-line.js

@@ -26,7 +26,7 @@
  * if (x < 0)
  *     x++;
  * else
-  *     x--;
+ *     x--;
  * ```
  * ```js
  * if (x < 0) {
@@ -47,7 +47,7 @@
  *     x++;
  * while(x < 0);
  * ```
-  * ```js
+ * ```js
  * do {
  *     x++;
  * }