doc: fix year in changelog

Most minor, 2018 should be 2019 for 10.15.3

PR-URL: #26584
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Vse Mozhet Byt <vsemozhetbyt@gmail.com>
Reviewed-By: Beth Griggs <Bethany.Griggs@uk.ibm.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>

Author: cprince

doc/changelogs/CHANGELOG_V10.md

@@ -54,7 +54,7 @@
 
 
 <a id="10.15.3"></a>
-## 2018-03-05, Version 10.15.3 'Dubnium' (LTS), @BethGriggs
+## 2019-03-05, Version 10.15.3 'Dubnium' (LTS), @BethGriggs
 
 ### Notable Changes