added docs for the prev auction info module

dev-docs/modules/previousAuctionInfo.md

@@ -0,0 +1,76 @@
+---
+layout: page_v2
+page_type: module
+title: Module - Previous Auction Info
+description: Allows publishers and bidders to collect and inject past auction data into future bid requests
+module_code : previousAuctionInfo
+display_name : Previous Auction Info
+enable_download : true
+sidebarType : 1
+
+---
+
+# Previous Auction Info
+
+## Overview
+
+The Previous Auction Info module enables functionality to collect prior auction data for participating bidders and publishers (This feature is `opt-in`, by default it is disabled).
+
+## How to Enable the Module
+
+A Publisher must do the following in order for the module to work:
+
+* Include the Previous Auction Info module within your Prebid.js build: [https://docs.prebid.org/download.html](https://docs.prebid.org/download.html)
+
+* Configure Prebid.js to enable the Previous Auction Info module:
+
+```javascript
+pbjs.setConfig({previousAuctionInfo: { enabled: true, bidders: ['bidderCode1', 'bidderCode2'], maxQueueLength: 10 }})
+```
+
+* Only valid bid requests submitted by bidders who have enabled the Previous Auction Info module will be permitted.
+
+If the requirements above are met, the flow for how the module works is as follows:
+
+1. A Prebid.js auction runs and completes.
+1. At the end of an auction, details about the auction are collected from each bidder using the module.
+1. If a Prebid bid wins, then the `rendered` field is updated to `1` to indicate this in the collected auction data for all bidders who bid on the same adunit within the same Prebid auction.
+1. During the next Prebid.js auction, if a bidder is included in previousAuctionInfo.bidders AND is included in the auction, then previous auction info data will be injected into the bidder's bid request of the new auction within the following path: `ortb2.ext.prebid.previousauctioninfo`.
+
+## Configuration Options
+
+{: .table .table-bordered .table-striped }
+| Field | Required? | Type | Description |
+|---|---|---|---|
+| previousAuctionInfo.enabled | yes | boolean | Enables/disables the module. |
+| previousAuctionInfo.bidders | no | array of strings  | Array of bidder codes to determine which bidders are allowed to receive collected previous auction info. Omitting this field will enable all bidders. |
+| previousAuctionInfo.maxQueueLength | no | integer  | The number of previous auction info payloads to store/collect per bidder before injecting these payloads into the bidstream. Any payloads collected for a bidder during one auction will be injected into the bidstream during the next auction that the same bidder participates in with valid bids. If this field is omitted, the value of this field is 10. |
+
+## Example of Previous Auction Info Payload
+
+`previousAuctionInfo` is an array of prior auction data catered to a specific bidder (if present, it will be added to a bidder's bid request). See below for an example of how the structure of the data looks (Note: Once collected previous auction data has been injected into the bid stream, then it is removed and no longer stored within the module):
+
+```javascript
+ortb2: {
+  ext: {
+    prebid: {
+      previousauctioninfo: [
+        {
+          bidderRequestId: "123abc",
+          bidId: "456def",
+          rendered: 1, // default is 0
+          source: "pbjs",
+          adUnitCode: "div-gpt-ad-123-0",
+          highestBidCpm: 0.052275935, // default is 0
+          bidderCpm: 0.04, // default is null
+          bidderOriginalCpm: 0.04, // default is null
+          bidderCurrency: "USD", // default is null
+          bidderOriginalCurrency: "USD", // default is null
+          bidderErrorCode: -1, // default is null
+          timestamp: 1739400860310
+        }
+      ]
+    }
+  }
+}
+```