[docgen] Update docs

Author: github-actions

doc/orgmode.txt

@@ -735,7 +735,7 @@ org_agenda_block_separator                *orgmode-org_agenda_block_separator*
 - Default: `-`
 
 Separator used to separate multiple agenda views generated by
-org_agendacustomcommands. To change the highlight, override
+|orgmode-org_agendacustomcommands|. To change the highlight, override
 `@org.agenda.separator` hl group.