blogdown 1.21

• Use the --renderToMemory flag by default for Hugo >= 0.123.0 when starting hugo server (thanks, @drmowinckels, #772). If you do not wish to use this flag by default, please see https://bookdown.org/yihui/blogdown/livereload.html on how to configure your own default flags for hugo server.

• Throw a clearer error when using the RStudio addin "Update Metadata" in the visual editor (thanks, @setgree, #769).