Simplify pick example

Old pick example included input array in command line, making `input` confusing
and redundant.

tests/man.test

@@ -249,7 +249,7 @@ pick(.a, .b.c, .x)
 {"a": 1, "b": {"c": 2, "d": 3}, "e": 4}
 {"a":1,"b":{"c":2},"x":null}
 
-[1,2,3,4] | pick(.[2], .[0], .[0])
+pick(.[2], .[0], .[0])
 [1,2,3,4]
 [1,null,3]