Update Etag guideline for collection values

Author: JeffreyRichter

azure/Guidelines.md

@@ -543,16 +543,16 @@ NOTE: It is a breaking change to add paging in the future
 ```json
 {
     "value": [
-       { "id": "Item 01", "etag": "0xabc", "price": 99.95, "sizes": null },
+       { "id": "Item 01", "etag": "\"abc\"", "price": 99.95, "sizes": null },
        { … },
        { … },
-       { "id": "Item 99", "etag": "0xdef", "price": 59.99, "sizes": null }
+       { "id": "Item 99", "etag": "\"def\"", "price": 59.99, "sizes": null }
     ],
     "nextLink": "{opaqueUrl}"
  }
 ```
 
-<a href="#collections-items-have-id-and-etag" name="collections-items-have-id-and-etag">:white_check_mark:</a> **DO** include the _id_ field and _etag_ field (if supported) for each item as this allows the customer to modify the item in a future operation.
+<a href="#collections-items-have-id-and-etag" name="collections-items-have-id-and-etag">:white_check_mark:</a> **DO** include the _id_ field and _etag_ field (if supported) for each item as this allows the customer to modify the item in a future operation. Note that the tag field _must_ have escaped-quotes embedded within it; for example "\"abc\"" or W/"\"abc\"".
 
 <a href="#collections-document-pagination-reliability" name="collections-document-pagination-reliability">:white_check_mark:</a> **DO** clearly document that resources may be skipped or duplicated across pages of a paginated collection unless the operation has made special provisions to prevent this (like taking a time-expiring snapshot of the collection).