AdGeneration: Align segment parameter with OpenRTB spec

This commit updates the AdGeneration bidder documentation to reflect a new specification for processing First Party Data segments (ortb2.site.content.data[].segment).

The updated specification defines two distinct behaviors:
1.  If only `segment[].id` is provided (e.g., `{ id: "1001" }`), the 'id' is treated as a pre-arranged classification code.
2.  If both `segment[].id` and `segment[].value` are provided (e.g., `{ id: "news", value: "sports" }`), the 'value' is read as the value for the 'id' key.

The documentation example has been updated to demonstrate both use cases.

Author: ss-toshihide-tajima

dev-docs/bidders/adgeneration.md

@@ -27,8 +27,11 @@ In release 1.6.4 and later, publishers should use the `ortb2` method of setting
 
 * ortb2.site.content.data[]
 
-If `ad-generation.jp` is specified for ortb2.site.content.data[].name and `546` is specified for ortb2.site.content.data[].ext.segtax,
-`ortb2.site.content.data[].segment[].name` and `ortb2.site.content.data[].segment[].value` can be any string value.
+If `ad-generation.jp` is specified for ortb2.site.content.data[].name and `546` is specified for ortb2.site.content.data[].ext.segtax, the segment array objects are processed as follows:
+- segment[].id: Required. Must be a string.
+- segment[].value: Optional. Must be a string.
+- If only id is provided (e.g., { id: "1001" }), the id is treated as a pre-arranged classification code agreed upon with the publisher.
+- If both id and value are provided (e.g., { id: "news_category", value: "Sports_Sumo" }), the value is read as the value associated with the id (key).
 
 Example first party data that's available to all bidders and all adunits:
 
@@ -43,9 +46,12 @@ pbjs.setConfig({
                         segtax: 546
                     },
                     segment: [
-                        { name: "news_category", value: "Sports_Sumo" },// name and value must be string types
-                        { name: "local_gourmet", value: "sushi" },
-                        { name: "location", value: "tokyo" }
+                        // Only id (required, string) is provided; treated as a classification code
+                        { id: "1001" }
+                        // Both id (required, string) and value (optional, string) are provided
+                        { id: "news_category", value: "Sports_Sumo" },
+                        { id: "local_gourmet", value: "sushi" },
+                        { id: "location", value: "tokyo" },
                     ]
                 }]
             }