#15575: Clarify tutorial description of when modules are executed.

Doc/tutorial/modules.rst

@@ -71,7 +71,8 @@ More on Modules
 
 A module can contain executable statements as well as function definitions.
 These statements are intended to initialize the module. They are executed only
-the *first* time the module is imported somewhere. [#]_
+the *first* time the module name is encountered in an import statement. [#]_
+(They are also run if the file is executed as a script.)
 
 Each module has its own private symbol table, which is used as the global symbol
 table by all functions defined in the module. Thus, the author of a module can