[saferecl.rcu.base] Fix description of "specialization"

tkoeppe · tkoeppe · commit 3608a50e381f · 2023-07-20T00:06:05.000+01:00
diff --git a/source/threads.tex b/source/threads.tex
@@ -11747,7 +11747,7 @@
 
 \pnum
 Objects of type \tcode{T} to be protected by RCU inherit from
-a specialization of \tcode{rcu_obj_base<T,D>}.
+a specialization \tcode{rcu_obj_base<T, D>} for some \tcode{D}.
 
 \begin{codeblock}
 namespace std {
