Add example in doc

site/_docs/reference.md

@@ -2729,7 +2729,7 @@ BigQuery's type system uses confusingly different names for types and functions:
 | o | EXTRACT(xml, xpath, [, namespaces ])           | Returns the XML fragment of the element or elements matched by the XPath expression. The optional namespace value that specifies a default mapping or namespace mapping for prefixes, which is used when evaluating the XPath expression
 | o | EXISTSNODE(xml, xpath, [, namespaces ])        | Determines whether traversal of a XML document using a specified xpath results in any nodes. Returns 0 if no nodes remain after applying the XPath traversal on the document fragment of the element or elements matched by the XPath expression. Returns 1 if any nodes remain. The optional namespace value that specifies a default mapping or namespace mapping for prefixes, which is used when evaluating the XPath expression.
 | m | EXTRACTVALUE(xml, xpathExpr))                  | Returns the text of the first text node which is a child of the element or elements matched by the XPath expression.
-| h s | FIND_IN_SET(string, stringArray)             | Returns the index (1-based) of the given *string* in the comma-delimited *stringArray*. Returns 0, if the given *string* was not found or if *string* contains a comma
+| h s | FIND_IN_SET(string, stringArray)             | Returns the index (1-based) of the given *string* in the comma-delimited *stringArray*. Returns 0, if the given *string* was not found or if *string* contains a comma. For example, FIND_IN_SET('bc', 'a,bc,def') returns 2
 | b | FLOOR(value)                                   | Similar to standard `FLOOR(value)` except if *value* is an integer type, the return type is a double
 | b | FORMAT_DATE(string, date)                      | Formats *date* according to the specified format *string*
 | b | FORMAT_DATETIME(string, timestamp)             | Formats *timestamp* according to the specified format *string*