Update bidder creation(java) doc with alias feature (#2886)

* Update bidder creation(java) doc with alias feature

* wordsmithing

Co-authored-by: Serhii Nahornyi <snahornyi@rubiconproject.com>
Co-authored-by: bretg <bgorsline@gmail.com>

prebid-server/developers/add-new-bidder-java.md

@@ -77,7 +77,7 @@ Create a file with the path `static/bidder-info/{bidder}.yaml` and begin with th
 
 ```yaml
 adapters:
-  {bidder}:
+  yourBidderCode:
     enabled: false
     endpoint: http://possible.endpoint
     pbs-enforces-gdpr: true
@@ -101,8 +101,8 @@ adapters:
       vendor-id: your_vendor_id
     usersync:
       url: your_bid_adapter_usersync_url
-      redirect-url: /setuid?bidder={bidder}&gdpr={%raw%}{{gdpr}}{%endraw%}&gdpr_consent={%raw%}{{gdpr_consent}}{%endraw%}&us_privacy={%raw%}{{us_privacy}}{%endraw%}
-      cookie-family-name: {bidder}
+      redirect-url: /setuid?bidder=yourBidderCode&gdpr={%raw%}{{gdpr}}{%endraw%}&gdpr_consent={%raw%}{{gdpr_consent}}{%endraw%}&us_privacy={%raw%}{{us_privacy}}{%endraw%}
+      cookie-family-name: yourBidderCode
       type: redirect
       support-cors: false
 ```
@@ -124,6 +124,63 @@ The url of your user syncer can make use of the following privacy policy macros
 
 - Change the `usersync:type` value to `redirect` or `iframe` specific to your bidder.
 
+### Create bidder alias
+If you want to add bidder that is an alias of existing bidder, you need just to update configuration of parent bidder:
+
+Example of adding bidder alias:
+```yaml
+adapters:
+  yourBidderCode:
+    enabled: false
+    endpoint: http://possible.endpoint
+    pbs-enforces-gdpr: true
+    pbs-enforces-ccpa: true
+    modifying-vast-xml-allowed: true
+    deprecated-names:
+    aliases: 
+      yourBidderAlias:
+        endpoint: http://possible.alias/endpoint
+        app-media-types:
+          - banner
+          - video
+        site-media-types:
+          - banner
+          - video
+        usersync:
+          cookie-family-name: yourBidderCode
+    meta-info:
+      maintainer-email: maintainer@email.com
+      app-media-types:
+        - banner
+        - video
+        - audio
+        - native
+      site-media-types:
+        - banner
+        - video
+        - audio
+        - native
+      supported-vendors:
+      vendor-id: your_vendor_id
+    usersync:
+      url: your_bid_adapter_usersync_url
+      redirect-url: /setuid?bidder=yourBidderCode&gdpr={%raw%}{{gdpr}}{%endraw%}&gdpr_consent={%raw%}{{gdpr_consent}}{%endraw%}&us_privacy={%raw%}{{us_privacy}}{%endraw%}
+      cookie-family-name: yourBidderCode
+      type: redirect
+      support-cors: false
+```
+
+Aliases are configured by adding child configuration object at `adapters.yourBidderCode.aliases.yourBidderAlias`
+
+Aliases support the same configuration options that their bidder counterparts support except `aliases` (i.e. it's not possible
+to declare alias of an alias). 
+
+{: .alert.alert-warning :}
+**Aliases cannot declare support for media types not supported by their parent bidders**<br />
+However aliases could narrow down media types they support.<br />
+For example: if the bidder is written to not support native site requests, then an alias cannot magically decide to change that;
+However, if a bidder supports native site requests, and the alias does not want to for some reason, it has the ability to remove that support.
+
 ### Bidder Parameters
 
 Your bid adapter might require extra information from the publisher to form a request to your bidding server. The bidder parameters JSON Schema codifies this information to allow Prebid Server to verify requests and to provide an API for third party configuration systems.