Update README in preparation for the 1.1 release

[frankkilcommins]

Things to include:

• include AsyncAPI in the opening paragraph
• update current version to 1.1.0 in the https://github.com/OAI/Arazzo-Specification#current-version---101 section
• update the image and add the soft version of the https://excalidraw.com/ meta to the repo.
• add tooling section before the "see in action section" and list current known tooling, but also point to openapi.tools for a more up-to-date community listing