📝 add documentation for JSON Lines (#3247)

doc/examples/json_lines.output

@@ -0,0 +1,4 @@
+{"name":"Gilbert","wins":[["straight","7♣"],["one pair","10♥"]]}
+{"name":"Alexa","wins":[["two pair","4♠"],["two pair","9♠"]]}
+{"name":"May","wins":[]}
+{"name":"Deloise","wins":[["three of a kind","5♣"]]}