[dcl.struct.bind] Insert missing space between words

Author: Andreas-Krug

source/declarations.tex

@@ -7515,7 +7515,7 @@
 the structured binding size of \tcode{E};
 the number of elements of the structured binding pack is
 the structured binding size of \tcode{E} less
-the number of non-pack elements in the\grammarterm{sb-identifier-list}.
+the number of non-pack elements in the \grammarterm{sb-identifier-list}.
 
 \pnum
 Let $\textrm{SB}_i$ denote