Updated mediawiki/extensions
Project: mediawiki/extensions/WikiLexicalData  164a44056df1c1f6f9a7dcdc36b3537ddc2b6d15

docgen

It now works with Doxygen version 1.8.1.2
Also tested with version 1.8.6

Patch 2: revised README.md to be doxygen version 1.8.1.2 compatible.

Change-Id: Ifb0adb7ce4d598546291bc601a3017da70c7dfee