[simulation/morse] Deactivate default 'doc' options

'doc' (and python-sphinx) has issues on multiple platforms because of the
python2/python3 conflicts between py-sphinx and morse, so disable the option by
default.

Fixes issue #13

simulation/morse/Makefile

@@ -17,7 +17,6 @@ CMAKE_ARGS+=		-DBUILD_HLA_SUPPORT=OFF
 
 # doc option
 PKG_SUPPORTED_OPTIONS+=	doc
-PKG_SUGGESTED_OPTIONS+=	doc
 PKG_OPTION_DESCR.doc?=	Install ${PKGBASE} documentation
 
 define PKG_OPTION_SET.doc