Correct typo in "detect_noop" documentation (#22039)

The documentation reads:

> You can disable this behavior by setting "detect_noop": false like this:

Followed by a code example, that originally set `"detect_noop": true`.

Please correct me if I got the change backwards (i.e. the paragraph should be changed to `true`), but this seems like it makes the most sense.

docs/reference/docs/update.asciidoc

@@ -184,7 +184,7 @@ POST test/type1/1/_update
     "doc" : {
         "name" : "new_name"
     },
-    "detect_noop": true
+    "detect_noop": false
 }
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 // CONSOLE