Updated Changelog.

CHANGELOG.md

@@ -5,6 +5,10 @@
 - Added CMake option `OGS_CPU_ARCHITECTURE`, #858, [donwloadable binaries](http://docs.opengeosys.org/download) build by Jenkins should now run on more CPUs
 - Added CMake options for Boost, VTK and Eigen (`OGS_LIB_BOOST`, ...) to specify if libs are searched on the system first, then build them locally (`Default`), or you can specify to just use system libs (`System`) or force a local build (`Local`)
 
+### Documentation
+
+- Added [offline viewable Doxygen documentation](http://docs.opengeosys.org/docs/devguide/documentation/offline-documentation-viewer)
+
 
 # 6.0.3