Add Splash/ Intro Video

Sophia has created a very nice video for panel-chat-examples

I think we should include the video in the README.md and index.md files.

Some things that could improve the video are

[ ] Showing the code just enough time that a user can stop the video if he/ she wants to study it.
[ ] Showing a correct response from the chat bot (HoloViz is not a package 😄 )
[ ] That the video shows the name panel-chat-examples on the first screen. That is the thing users will see before they play the video.

Other ideas

[ ] Including logos from some of the things we support like Pandas, LangChain, Mistral, OpenAI etc
[ ] Adding a show tour of screenshots of some of the most impressive examples like he langchain_pdf_assistant.

holoviz-topics / panel-chat-examples