[basic.lookup.unqual] Fix placement of cross reference

Author: tkoeppe

source/basic.tex

@@ -1756,7 +1756,7 @@
 \pnum
 In a friend declaration \grammarterm{declarator}
 whose \grammarterm{declarator-id} is a \grammarterm{qualified-id}
-whose lookup context is\iref{basic.lookup.qual} a class or namespace $S$,
+whose lookup context\iref{basic.lookup.qual} is a class or namespace $S$,
 lookup for an unqualified name
 that appears after the \grammarterm{declarator-id}
 performs a search in the scope associated with $S$.