bpo-35224: Additional documentation for Assignment Expressions (GH-15935)



Add or update assignment expression documentation for:
- FAQ - Design
- Reference - Expressions
- Reference - Lexical Analysis


https://bugs.python.org/issue35224



Automerge-Triggered-By: @matrixise
diff --git a/Doc/reference/expressions.rst b/Doc/reference/expressions.rst
index 73a2f27..d9db33a 100644
--- a/Doc/reference/expressions.rst
+++ b/Doc/reference/expressions.rst
@@ -1784,6 +1784,8 @@
 +-----------------------------------------------+-------------------------------------+
 | Operator                                      | Description                         |
 +===============================================+=====================================+
+| ``:=``                                        | Assignment expression               |
++-----------------------------------------------+-------------------------------------+
 | :keyword:`lambda`                             | Lambda expression                   |
 +-----------------------------------------------+-------------------------------------+
 | :keyword:`if <if_expr>` -- :keyword:`!else`   | Conditional expression              |
diff --git a/Doc/reference/lexical_analysis.rst b/Doc/reference/lexical_analysis.rst
index 7e1e17e..c0e13b5 100644
--- a/Doc/reference/lexical_analysis.rst
+++ b/Doc/reference/lexical_analysis.rst
@@ -887,7 +887,7 @@
 
 
    +       -       *       **      /       //      %      @
-   <<      >>      &       |       ^       ~
+   <<      >>      &       |       ^       ~       :=
    <       >       <=      >=      ==      !=