Remove comment for PHOBOS macro (it's pending removal)

Author: ntrel

dlang.org.ddoc

@@ -331,7 +331,6 @@ _=
 PC=$(TC p, $1, $+)
 _=
 
-$(COMMENT Should be used only when link text is not std.$1.$2 - use REF instead)
 PHOBOS=$(SPANC phobos, $(AHTTPS dlang.org/phobos/std_$1.html#$2, $(TAIL $+)))
 PHOBOSSRC=$(SPANC phobos_src, $(AHTTPS github.com/dlang/phobos/blob/master/$0, $0))
 _=