core: Remove spurious "[description]" placeholder from documentation
core: Remove spurious "[description]" placeholder from documentation

Also fixup the typehint to reflect the native primitive instead of
the object constructor.

Change-Id: Idbcd3fe7ccac5cabf292a0d9a420f43f2b43d3b7
wikimedia/oojs-ui,wikimedia/oojs-ui,wikimedia/oojs-ui,wikimedia/oojs-ui