R: Vignettes and other documentation

# Vignettes and other documentation

## Vignettes from package 'chattr'

chattr::backend-llamagpt |  | Interact with local models | HTML | source | R code
chattr::copilot-chat |  | Interact with GitHub Copilot Chat | HTML | source | R code
chattr::openai-gpt |  | Interact with OpenAI GPT models | HTML | source | R code
chattr::other-interfaces |  | Other interfaces | HTML | source | R code
chattr::prompt_defaults |  | Modify prompt enhancements | HTML | source | R code