pbs adapter: request compressions

dev-docs/modules/prebidServer.md

@@ -97,7 +97,7 @@ There are many configuration options for s2sConfig:
 | `adapterOptions` | Optional | Object | Arguments will be added to resulting OpenRTB payload to Prebid Server in every impression object at request.imp[].ext.BIDDER. See the example above. |
 | `extPrebid` | Optional | Object | Arguments will be added to resulting OpenRTB payload to Prebid Server in request.ext.prebid. See the examples below. |
 | `customHeaders` | Optional | Object | These custom headers will be included in the XHR call to the bidder's endpoint. This will allow you to send data specific to your use case. The format consists of an object where the keys represent the header names and the values correspond to the respective header values. Here is an example how a customHeader object might look like - `{"Header1": "Value1", "Header2": "Value2"}`|
-| `endpointCompression` | Optional | Boolean | Enable gzip compression of outgoing requests when supported. | `true` |
+| `endpointCompression` | Optional | Boolean | Gzip compress the auction request payload when supported and debug mode is off. Adds `gzip=1` to the request URL. |
 | `filterBidderlessCalls` | Optional | Boolean | When `true`, ad units that have no bidders defined are excluded from Prebid Server requests. Defaults to `false`. | `true` |
 
 If `endpoint` and `syncEndpoint` are objects, these are the supported properties:
@@ -115,6 +115,7 @@ If `endpoint` and `syncEndpoint` are objects, these are the supported properties
 - If `bidders` is omitted, only adUnits that also omit bidders will be sent to Prebid Server. See the [stored impressions](#stored-imp) example below.
 - If the `s2sConfig` timeout is not specified, Prebid Server will utilize a configured default for `tmax`.
 - When using the `endpoint` or `syncEndpoint` object configs, you should define both properties.  If either property is not defined, Prebid Server requests for that type of user will not be made.  If you do not need to distinguish endpoints for consent reasons, you can simply define the same URL value in both fields or use the String version of the field (which is configured to use defined URL for all users).
+- When `endpointCompression` is enabled, Prebid.js compresses the request body sent to Prebid Server and appends `gzip=1` to the endpoint URL. This feature is skipped when debug mode is active or the browser lacks GZIP support. Do not use if your PBS Host does not yet support gzip request compression.
 - <a name="allowUnknownBidderCodes" ></a> When `allowUnknownBidderCodes` is `true`, bidders that have not been explicitly requested in [`adUnit.bids`](../adunit-reference.html#adunitbids) may take part in the auction. This can break custom logic that relies on the availability of a bid request object for any given bid. Known scenarios where custom code won't get the request when there's an "unknown bidder":
   - There will not be a [`bidRequested`](/dev-docs/publisher-api-reference/getEvents.html) event.
   - In the [MASS custom renderers](/dev-docs/modules/mass.html#configuration-parameters) module, `payload.bidRequest` will be undefined.