* gptel.el: Mention Anthropic in the package description.
* gptel-anthropic.el (gptel-anthropic, gptel-make-anthropic,
gptel--parse-response, gptel--request-data, gptel--parse-buffer,
gptel-curl--parse-stream): Add support for Anthropic AI's Claude 3
models.
* README.org: Add instructions for using Anthropic AI's Claude 3
models.
