Add Maven publishing configuration for Java SDK (#469)

Author: tstanmay13

fern/products/sdks/overview/java/configuration.mdx

@@ -85,6 +85,7 @@ config:
 </ParamField>
 
 <ParamField path="publish-to" type="'central' | 'ossrh'" required={false} toc={true}>
+Publish target for Maven packages. Use `central` for Maven Central Portal or `ossrh` for legacy Nexus Repository.
 </ParamField>
 
 <ParamField path="wrapped-aliases" type="boolean" default="false" required={false} toc={true}>

fern/products/sdks/overview/java/publishing-to-maven-central.mdx

@@ -71,7 +71,7 @@ groups:
       groupId:artifactId` field. This specifies how your Java SDK will be
       published and referenced in the Maven Central respository. 
 
-      ```yaml {8}
+      ```yaml {8,11}
       groups: 
         java-sdk:
           generators:
@@ -80,6 +80,8 @@ groups:
               output:
                 location: maven
                 coordinate: com.company:sdk-name # <company name in reverse domain name format>:<SDK name>
+              config:
+                publish-to: central  # Use 'central' for new Sonatype Central Portal (most common)
               github: 
                 repository: your-org/company-java
       ```