MERGE command is not mentioned in the list of commands for variable substitution

The following documentation comment has been logged on the website:

Page: https://www.postgresql.org/docs/18/plpgsql-implementation.html
Description:

In the last paragraph of the section 41.11.1. "Variable Substitution" there
is such a sentence --
"Variable substitution currently works only in SELECT, INSERT, UPDATE,
DELETE, and commands containing one of these..."
https://www.postgresql.org/docs/current/plpgsql-implementation.html#PLPGSQL-VAR-SUBST
But experiments showed that variable substitution works for MERGE command
too.