[associative.reqmts.general] Fix typo (#7069)

Author: apolukhin

source/containers.tex

@@ -2636,7 +2636,7 @@
 \tcode{a2} denotes a value of a type with nodes compatible with type
 \tcode{X} (\tref{container.node.compat}),
 \item
-\tcode{b} denotes a value or type \tcode{X} or \tcode{const X},
+\tcode{b} denotes a value of type \tcode{X} or \tcode{const X},
 \item
 \tcode{u} denotes the name of a variable being declared,
 \item