R: Vignettes and other documentation

# Vignettes and other documentation

## Vignettes from package 'did'

did::TWFE |  | Problems with two-way fixed-effects event-study regressions | HTML | source | R code
did::did-basics |  | Getting Started with the did Package | HTML | source | R code
did::extensions |  | Writing Extensions to the did Package | HTML | source | R code
did::multi-period-did |  | Introduction to DiD with Multiple Time Periods | HTML | source | R code
did::pre-testing |  | Pre-Testing in a DiD Setup using the did Package | HTML | source | R code