Ref Guide: also fix old link to PDFBox

Author: ctargett

solr/solr-ref-guide/src/uploading-data-with-solr-cell-using-apache-tika.adoc

@@ -18,7 +18,7 @@
 
 If the documents you need to index are in a binary format, such as Word, Excel, PDFs, etc., Solr includes a request handler which uses http://tika.apache.org/[Apache Tika] to extract text for indexing to Solr.
 
-Solr uses code from the Tika project to provide a framework for incorporating many different file-format parsers such as http://incubator.apache.org/pdfbox/[Apache PDFBox] and http://poi.apache.org/index.html[Apache POI] into Solr itself.
+Solr uses code from the Tika project to provide a framework for incorporating many different file-format parsers such as http://pdfbox.apache.org/[Apache PDFBox] and http://poi.apache.org/index.html[Apache POI] into Solr itself.
 
 Working with this framework, Solr's `ExtractingRequestHandler` uses Tika internally to support uploading binary files
 for data extraction and indexing. Downloading Tika is not required to use Solr Cell.