Update citation dates for v4.2

Author: daslerr

source/meta/kernel-4.2/index.html.md

@@ -8,12 +8,12 @@ documentation_url: /meta/kernel-4.2/doc/DataCite-MetadataKernel_v4.2.pdf
 ---
 
 ## Documentation
-DataCite Metadata Working Group. (2018). DataCite Metadata Schema Documentation for the Publication and Citation of Research Data. Version 4.2. DataCite e.V. https://doi.org/10.5438/bmjt-bx77
+DataCite Metadata Working Group. (2019). DataCite Metadata Schema Documentation for the Publication and Citation of Research Data. Version 4.2. DataCite e.V. https://doi.org/10.5438/bmjt-bx77
 
 <a href="doc/DataCite-MetadataKernel_v4.2.pdf" class="btn">Download PDF</a>
 
 ## Schema
-DataCite Metadata Working Group. (2017). DataCite Metadata Schema for the Publication and Citation of Research Data. Version 4.2. DataCite e.V. http://doi.org/10.5438/rv0g-av03
+DataCite Metadata Working Group. (2019). DataCite Metadata Schema for the Publication and Citation of Research Data. Version 4.2. DataCite e.V. http://doi.org/10.5438/rv0g-av03
 
 <a href="metadata.xsd" class="btn">View XSD</a>