Update default sections of the Area Forecast Discussion provided to different report types

docs/config.md

@@ -251,7 +251,7 @@ reports:
       - id: area_forecast_discussion
         options:
           sections:
-            - short_term
+            - long_term
       - spc_convective_discussion
       - daily_planning
       - hourly_forecast
@@ -292,7 +292,8 @@ Unknown reports, unknown modules, duplicate modules, incompatible report/module
 combinations, duplicate stanza names, and invalid options fail config loading.
 `area_forecast_discussion.options.sections` may contain `product`,
 `key_messages`, `short_term`, and `long_term`. Empty or omitted `sections`
-includes all available AFD sections.
+includes all available AFD sections. Default report definitions may choose a
+smaller report-specific subset, such as daily reports using only `long_term`.
 
 The module registry accepts all module IDs documented in
 [Module Contract Internals](internal/module.md). Unknown or unimplemented