Update FORMAT-GUIDE.md (#547)
Update FORMAT-GUIDE.md (#547)

* Update FORMAT-GUIDE.md

Added an iterm about YouTube Video Embeds

* Update FORMAT-GUIDE.md
googlecodelabs/tools,Qwiklabs/codelab-tools,googlecodelabs/tools,googlecodelabs/tools,Qwiklabs/codelab-tools,Qwiklabs/codelab-tools,googlecodelabs/tools,Qwiklabs/codelab-tools