This was already supported in sandcastle. As described on [microsoft uservoice](https://visualstudio.uservoice.com/forums/121579-visual-studio-2015/suggestions/3745102-add-intellisense-support-for-the-inheritdoc-ta). Related issue for [Roslyn](https://github.com/dotnet/roslyn/issues/67).
This was already supported in sandcastle.
As described on microsoft uservoice. Related issue for Roslyn.