Improve javadocs by adding links to dependency docs

By: md_5 <git@md-5.net>

paper-api/pom.xml

@@ -182,6 +182,18 @@
                     <shadedArtifactAttached>true</shadedArtifactAttached>
                 </configuration>
             </plugin>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-javadoc-plugin</artifactId>
+                <version>3.2.0</version>
+                <configuration>
+                    <links>
+                        <link>https://guava.dev/releases/21.0/api/docs/</link>
+                        <link>https://javadoc.io/doc/org.yaml/snakeyaml/1.26/</link>
+                        <link>https://javadoc.io/doc/org.jetbrains/annotations/19.0.0/</link>
+                    </links>
+                </configuration>
+            </plugin>
         </plugins>
     </build>