chore(docs): Add demo for canvas

[rebeccaalpert]

Fixes #899

See https://chatbot-pr-chatbot-901.surge.sh/extensions/chatbot/overview/demo/canvas/ for demo.

[patternfly-build]

Preview: https://chatbot-pr-chatbot-901.surge.sh

A11y report: https://chatbot-pr-chatbot-901-a11y.surge.sh

[kaylachumley]

Thanks for working on this! This is looking really good. A few notes/adjustments per our discussion from yesterday.

• Make the "generated by AI" label clickable with a popover that's initiated upon click. Here is a screenshot of the text that needs to be in the popover:

• I spoke to nicole about where this demo could live for better visibility and we agreed that it would fit nicely under our Patterns section in the left nav. Can you change the section field in the meta data so this lives under patterns?

• Add in a redo and undo action(icon button) in the code editor toolbar

• Add in a export icon button in the code editor toolbar

• Add in a save icon button in the code editor toolbar

• Add an "x" icon button into the left chatbot header

• Add in the original history drawer icon button in the chatbot header

• Add the "Always review AI-generated content prior to use." footnote below the message bar