[range.istream.iterator] Add missing space.

Author: tkoeppe

source/ranges.tex

@@ -2888,7 +2888,7 @@
 \effects
 Equivalent to:
 \begin{codeblock}
-*@\exposid{parent_}@->@\exposid{stream_}@>> @\exposid{parent_}@->@\exposid{object_}@;
+*@\exposid{parent_}@->@\exposid{stream_}@ >> @\exposid{parent_}@->@\exposid{object_}@;
 return *this;
 \end{codeblock}
 \end{itemdescr}