add api doc link to 2.14

Author: jef-n

doc/index.dox

@@ -28,6 +28,7 @@ See \ref api_break for information about incompatible changes to API between rel
 
 Earlier versions of the documentation are also available on the QGIS
 website:
+<a href="http://qgis.org/api/2.14">2.14 (LTR)</a>,
 <a href="http://qgis.org/api/2.12">2.12</a>,
 <a href="http://qgis.org/api/2.10">2.10</a>,
 <a href="http://qgis.org/api/2.8">2.8 (LTR)</a>,