docs: add `multiple` to docs

May need to go into more detail since the result object is significantly different.

README.md

@@ -357,7 +357,8 @@ options within the `decoder` are for debugging/visualization purposes only.
   showPattern: false,
   readers: [
     'code_128_reader'
-  ]
+  ],
+  multiple: false
 }
 ```
 
@@ -380,6 +381,10 @@ more possible clashes, or false-positives. One should take care of the order
 the readers are given, since some might return a value even though it is not
 the correct type (EAN-13 vs. UPC-A).
 
+The `multiple` property tells the decoder if it should stop after finding a single result.  If multiple is set to
+`true`, the `result` object will have a `barcodes` array, each of which is a `result` object with it's own `codeResult`,
+`box`, `line`, etc.
+
 The remaining properties `drawBoundingBox`, `showFrequency`, `drawScanline` and
 `showPattern` are mostly of interest during debugging and visualization.