docs(design-guidelines): Adds guidelines around starting new chats.

[edonehoo]

Closes #437

link to docs: https://chatbot-pr-chatbot-793.surge.sh/extensions/chatbot/overview/design-guidelines#starting-a-new-chat

[patternfly-build]

Preview: https://chatbot-pr-chatbot-793.surge.sh

A11y report: https://chatbot-pr-chatbot-793-a11y.surge.sh

[edonehoo]

@kaylachumley could you take a look at what I put together at https://chatbot-pr-chatbot-793.surge.sh/extensions/chatbot/overview/design-guidelines#starting-a-new-chat and let me know if you think it looks in line with what we'd want to recommend design-wise?

Also tagging @thatblindgeye to get the full crew review

[kaylachumley]

The guidelines and image will need swapped for this guy! i attached a lil screenshot explaining - i suppose the user could wire up the new chat to be in that options menu displayed but thats not the recommended pattern as of now. Also a tooltip would appear not a popover - ignore my component mix up in the description