Extract code snippets from how-to-get-the-titles-of-all-the-slides-in-a-presentation.md

Extract the code snippets from [docs/presentation/how-to-get-the-titles-of-all-the-slides-in-a-presentation.md](https://github.com/OfficeDev/open-xml-docs/blob/main/docs/presentation/how-to-get-the-titles-of-all-the-slides-in-a-presentation.md) and use docfx snippets to retrieve them from the samples folder and audit the text.