Add "dotnet new" templates guidance to public docs

We need to publish the information [here](https://github.com/Azure/azure-functions-templates/wiki/Using-the-templates-directly-via-dotnet-new) to the public Microsoft Docs site.

Start with the linked Azure Functions templates wiki page, then identify the appropriate public Microsoft Docs location and its contribution process. Done means the information about using the templates through dotnet new is published on Microsoft Docs; the issue names no repository file or test.

Written by the indexing model from the issue text.