[PATCH] docs/misra: add 13.6 to rules.rst

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

As agreed during MISRA C meetings, add Rule 13.6 to rules.rst.

Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxx>
---
There was a request to expand the scope to also include alignof and
typeof. Depending on whether the MISRA C scanners support it, and under
which rules violations will be listed, rules.rst will be updated
accordingly (either updating the notes section of 13.6 or adding a new
entry.)

diff --git a/docs/misra/rules.rst b/docs/misra/rules.rst
index 1e134ccebc..415b5b63c3 100644
--- a/docs/misra/rules.rst
+++ b/docs/misra/rules.rst
@@ -445,6 +445,12 @@ maintainers if you want to suggest a change.
      - Initializer lists shall not contain persistent side effects
      -
 
+   * - `Rule 13.6 
<https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_13_06.c>`_
+     - Required
+     - The operand of the sizeof operator shall not contain any
+       expression which has potential side-effects
+     -
+
    * - `Rule 14.1 
<https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_14_01.c>`_
      - Required
      - A loop counter shall not have essentially floating type