[Docs] Fix incomplete URLs (#28528)

docs/plugins/authors.asciidoc

@@ -5,9 +5,9 @@
 
 The Elasticsearch repository contains examples of:
 
-* a https://github.com/elastic/elasticsearch/tree/master/plugins/custom-settings[Java plugin]
+* a https://github.com/elastic/elasticsearch/tree/master/plugins/examples/custom-settings[Java plugin]
   which contains a plugin with custom settings.
-* a https://github.com/elastic/elasticsearch/tree/master/plugins/rest-handler[Java plugin]
+* a https://github.com/elastic/elasticsearch/tree/master/plugins/examples/rest-handler[Java plugin]
   which contains a plugin that registers a Rest handler.
 * a https://github.com/elastic/elasticsearch/tree/master/plugins/examples/rescore[Java plugin]
   which contains a rescore plugin.