ATS-identityLinkIdSystem - add explanation for new use3P config param…

…eter (#2853)

* ATS-identityLinkIdSystem - add explanation for new use3P config parameter

* Update userId.md

* Update userId.md

Co-authored-by: MartianTribe <steve@martiantribe.com>

dev-docs/modules/userId.md

@@ -500,7 +500,7 @@ The IdentityLink privacy policy is at [https://liveramp.com/privacy/service-priv
 | name | Required | String | `"identityLink"` | `"identityLink"` |
 | params | Required for Id Link | Object | Details for identityLink initialization. | |
 | params.pid | This parameter is required for IdentityLink | String | This is the placementId, value needed for obtaining user’s IdentityLink envelope
-
+| params.use3P | This parameter is not required for IdentityLink | Boolean | Property for choosing should 3P Liveramp envelope endpoint be fired or not, in order to get IdentityLink envelope
 
 #### IdentityLink Examples
 
@@ -513,7 +513,8 @@ pbjs.setConfig({
         userIds: [{
             name: "identityLink",
             params: {
-                pid: '999'             // Set your real identityLink placement ID here
+                pid: '999',             // Set your real identityLink placement ID here
+                // use3P: true/false    // If you want to use 3P endpoint to retrieve the envelope. If you do not set this property to true, 3P endpoint will not be fired. By default this property is undefined and 3P request are not fired.
             },
             storage: {
                 type: "cookie",
@@ -534,7 +535,8 @@ pbjs.setConfig({
         userIds: [{
             name: "identityLink",
             params: {
-                pid: '999'          // Set your real identityLink placement ID here
+                pid: '999',          // Set your real identityLink placement ID here
+                // use3P: true/false    // If you want to use 3P endpoint to retrieve the envelope. If you do not set this property to true, 3P endpoint will not be fired. By default this property is undefined and 3P request are not fired.
             },
             storage: {
                 type: "html5",