docs(expression.py): describe new name & value productions

Author: lovetheguitar

src/_pytest/mark/expression.py

@@ -8,12 +8,15 @@
 not_expr:   'not' not_expr | '(' expr ')' | ident ('(' name '=' value ( ', ' name '=' value )*  ')')?
 
 ident:      (\w|:|\+|-|\.|\[|\]|\\|/)+
+name:       a valid ident, but not a reserved keyword
+value:      (unescaped) string literal | (-)?[0-9]+ | 'False' | 'True' | 'None'
 
 The semantics are:
 
 - Empty expression evaluates to False.
 - ident evaluates to True or False according to a provided matcher function.
 - or/and/not evaluate according to the usual boolean semantics.
+- ident with parentheses and keyword arguments evaluates to True or False according to a provided matcher function.
 """
 
 from __future__ import annotations