Fix Javadoc typo in JsonHelper (#1215)

There is an "if" in a sentence where it should not be.

src/main/java/org/kiwiproject/json/JsonHelper.java

@@ -57,7 +57,7 @@
  * A bunch of utilities to make it easier to work with JSON.
  * <p>
  * One specific note on methods that accept paths. The syntax used to indicate array paths consists of the
- * array property name, followed by a period, followed by the array index in square brackets. For example, if
+ * array property name, followed by a period, followed by the array index in square brackets. For example,
  * to find the first value in an array property {@code luckyNumbers}, the path is {@code luckyNumbers.[0]}.
  * Similarly, to find the 13th lucky number the path is {@code luckyNumbers.[12]}.
  * <p>