[inplace.vector.overview] Add missing ',' in comment

Author: Andreas-Krug

source/containers.tex

@@ -9638,7 +9638,7 @@
     constexpr const_reverse_iterator crbegin() const noexcept;
     constexpr const_reverse_iterator crend()   const noexcept;
 
-    // \ref{inplace.vector.capacity} size/capacity
+    // \ref{inplace.vector.capacity}, size/capacity
     constexpr bool empty() const noexcept;
     constexpr size_type size() const noexcept;
     static constexpr size_type max_size() noexcept;