amp clarification

dev-docs/show-prebid-ads-on-amp-pages.md

@@ -37,7 +37,7 @@ To set up Prebid to serve ads into your AMP pages, you'll need:
 
 + An account with a [Prebid Server][PBS] instance
 + One or more Prebid Server Stored Bid Requests. A Stored Bid Request is a partial OpenRTB JSON request which:
-    + Specifies properties like timeout and price granularity
+    + Specifies properties like currency, schain, price granularity, etc.
     + Contains a list of demand partners and their respective parameters
 + An AMP page containing at least one amp-ad element for an AMP ad network that supports Fast Fetch and AMP RTC
 
@@ -52,19 +52,38 @@ To set up Prebid to serve ads into your AMP pages, you'll need:
 
 You will have to create at least one Stored Request for Prebid Server.  Valid Stored Requests for AMP pages must contain an `imp` array with exactly one element.  It is not necessary to include a `tmax` field in the Stored Request, as Prebid Server will always use the smaller of the AMP default timeout (1000ms) and the value passed via the `timeoutMillis` field of the `amp-ad.rtc-config` attribute (explained in the next section).
 
-An example Stored Request is given below:
+An example Stored Request is given below. You'll see that the Stored Request contains some important info
+that doesn't come from /amp parameters:
+
+- cur
+- schain
+- ext.prebid.cache.bids - needed to let Prebid Server know that you want it to store the result in PBC
+- ext.prebid.targeting.pricegranularity - needed to let Prebid Server know how to calculate the price bucket
+- ext.prebid.aliases
+- bidders and their parameters
 
 ```html
 
 {
     "id": "some-request-id",
+    "cur": ["USD"],
+    "source": {
+        "ext": {
+            "schain": {
+                ...
+            }
+        }
+    },
     "site": {
-        "page": "prebid.org"
+        "page": "prebid.org"  // will be overridden by the 'curl' parameter on /amp endpoint
     },
     "ext": {
         "prebid": {
+            "cache": {
+                "bids": {}
+            },
             "targeting": {
-                "pricegranularity": {  // This is equivalent to the deprecated "pricegranularity": "medium"
+                "pricegranularity": {  // This is equivalent to "pricegranularity": "medium"
                     "precision": 2,
                     "ranges": [{
                         "max": 20.00,
@@ -86,10 +105,10 @@ An example Stored Request is given below:
                 ]
             },
             "ext": {
-                "appnexus": {
+                "bidderA": {
                     // Insert parameters here
                 },
-                "rubicon": {
+                "bidderB": {
                     // Insert parameters here
                 }
             }
@@ -98,6 +117,7 @@ An example Stored Request is given below:
 }
 
 ```
+This basic OpenRTB record will be enhanced by the parameters from the call to the [/amp endpoint](prebid-server/endpoints/openrtb2/amp.html).
 
 ### AMP content page