bpo-45619: documentation of execution model: clarify and update bindi…

…ng summary (#29232)

This does two changes that are quite related.

0. it add that variable binding can occur in pattern matching, an update of 3.10
which seems to have been omitted from the list of bindings
1. Given how long the sentence already was, with even subcases in the middle of
the sentence, the commit breaks the sentence into an actual list.

Doc/reference/executionmodel.rst

@@ -56,15 +56,25 @@ Binding of names
 
 .. index:: single: from; import statement
 
-The following constructs bind names: formal parameters to functions,
-:keyword:`import` statements, class and function definitions (these bind the
-class or function name in the defining block), and targets that are identifiers
-if occurring in an assignment, :keyword:`for` loop header, or after
-:keyword:`!as` in a :keyword:`with` statement or :keyword:`except` clause.
-The :keyword:`!import` statement
-of the form ``from ... import *`` binds all names defined in the imported
-module, except those beginning with an underscore.  This form may only be used
-at the module level.
+The following constructs bind names:
+
+* formal parameters to functions,
+* class definitions,
+* function definitions,
+* assignment expressions,
+* :ref:`targets <assignment>` that are identifiers if occurring in
+  an assignment:
+
+  + :keyword:`for` loop header,
+  + after :keyword:`!as` in a :keyword:`with` statement, :keyword:`except`
+    clause or in the as-pattern in structural pattern matching,
+  + in a capture pattern in structural pattern matching
+
+* :keyword:`import` statements.
+
+The :keyword:`!import` statement of the form ``from ... import *`` binds all
+names defined in the imported module, except those beginning with an underscore.
+This form may only be used at the module level.
 
 A target occurring in a :keyword:`del` statement is also considered bound for
 this purpose (though the actual semantics are to unbind the name).