override single section type per document: metanorma/metanorma-stando…

…c#939

author/topics/sections.adoc

@@ -122,7 +122,16 @@ For these types of sections, enter them without
 * Index: `[index]`
 * Annexes: `[appendix]`
 
-NOTE: Documents can contain only one Abstract, one Acknowledgements section, and one Index.
+[NOTE]
+--
+Documents can contain only one Abstract, one Acknowledgements section, and one Index.
+In most flavours and documents types, documents can only contain one Terms and Definitions section.
+If a second matching clause is found, it is treated as a normal clause.
+
+However, this can be overridden by specifying the section type in a `heading` attribute:
+this is interpreted as the user explicitly wanting that section type to 
+apply  [added in https://github.com/metanorma/metanorma-standoc/releases/tag/v2.10.0].
+--
 
 The following example indicates usage of the section titles.