[2.7] bpo-33852: Remove misplaced parentheses around 'list'. (GH-7672) (#7716)

'expresson list' refers to the grammar term 'expression_list' in the subscription production..
(cherry picked from commit 4fddd4e)

Co-authored-by: Andrés Delfino <[email protected]>

Author: andresdelfino

Doc/reference/expressions.rst

@@ -581,7 +581,7 @@ whose value is one of the keys of the mapping, and the subscription selects the
 value in the mapping that corresponds to that key.  (The expression list is a
 tuple except if it has exactly one item.)
 
-If the primary is a sequence, the expression (list) must evaluate to a plain
+If the primary is a sequence, the expression list must evaluate to a plain
 integer.  If this value is negative, the length of the sequence is added to it
 (so that, e.g., ``x[-1]`` selects the last item of ``x``.)  The resulting value
 must be a nonnegative integer less than the number of items in the sequence, and