DOC-2486: Add requires 7.1v admon to Revision History Diff API (#3391)

Author: Farzad Hayat

modules/ROOT/partials/plugin-apis/revisionhistory-apis.adoc

@@ -9,6 +9,8 @@ interface PluginAPI {
 === `diff`
 Returns a HTML string with annotations indicating the changes in `originalHTML` relative to `changedHTML`. The styling of annotations can be customized via xref:revisionhistory_diff_classes[`+revisionhistory_diff_classes+`] option.
 
+include::partial$misc/admon-requires-7.1v.adoc[]
+
 == Example
 [source,js]
 ----