add actions to expr and rule index

Author: conrad-watt

document/core/appendix/index-rules.rst

@@ -110,6 +110,7 @@ Execution
 ===============================================  ===============================================================================
 Construct                                        Judgement
 ===============================================  ===============================================================================
-:ref:`Instruction <exec-instr>`                  :math:`S;F;\instr^\ast \stepto S';F';{\instr'}^\ast`
-:ref:`Expression <exec-expr>`                    :math:`S;F;\expr \stepto  S';F';\expr'`
+:ref:`Instruction <exec-instr>`                  :math:`S;F;\instr^\ast \stepto^{\act^\ast} S';F';{\instr'}^\ast`
+:ref:`Expression <exec-expr>`                    :math:`S;F;\expr \stepto^{\act^\ast}  S';F';\expr'`
+:ref:`Configuration <syntax-reduction>`          :math:`\config \stepto^{\evt}  \config'`
 ===============================================  ===============================================================================

document/core/exec/instructions.rst

@@ -4210,8 +4210,8 @@ An :ref:`expression <syntax-expr>` is *evaluated* relative to a :ref:`current <e
 The value :math:`\val` is the result of the evaluation.
 
 .. math::
-   S; F; \instr^\ast \stepto S'; F'; \instr'^\ast
-   \qquad (\iff S; F; \instr^\ast~\END \stepto S'; F'; \instr'^\ast~\END)
+   S; F; \instr^\ast \stepto^{\act^\ast} S'; F'; \instr'^\ast
+   \qquad (\iff S; F; \instr^\ast~\END \stepto^{\act^\ast} S'; F'; \instr'^\ast~\END)
 
 .. note::
    Evaluation iterates this reduction rule until reaching a value.