Polish roxygen2 markdown experience

* Turn on by default
* Refine use_roxygen_md() to just suggest using roxygen2md

Fixes #911

NEWS.md

@@ -1,5 +1,8 @@
 # usethis (development version)
 
+* `create_package()` now turns markdown processing for roxygen2 on by default 
+  (#911).
+
 * `edit_file()` and `use_test()` gain an `open` parameter that allows you to
   control whether or not the function is opened for editing by the user (#817).
 

R/description.R

@@ -78,7 +78,8 @@ use_description_defaults <- function() {
       "Authors@R" = 'person("First", "Last", , "first.last@example.com", c("aut", "cre"), comment = c(ORCID = "YOUR-ORCID-ID"))',
       License = " `use_mit_license()`, `use_gpl3_license()` or friends to pick a license",
       Encoding = "UTF-8",
-      LazyData = "true"
+      LazyData = "true",
+      Roxygen = "list(markdown = TRUE)"
     )
   )
 }

R/roxygen.R

@@ -1,10 +1,9 @@
 #' Use roxygen with markdown
 #'
-#' You'll need to manually re-document once enabled. If you are already using
-#' roxygen2, but not with markdown, the
-#' [roxygen2md](https://roxygen2md.r-lib.org) package will be used to
-#' convert many Rd expressions to markdown. The package uses heuristics, so
-#' you'll need to check the results.
+#' If you are already using roxygen2, but not with markdown, you'll need to use
+#' [roxygen2md](https://roxygen2md.r-lib.org) to convert existing Rd
+#' expressions to markdown. The conversion is not perfect, so make sure
+#' to check the results.
 #'
 #' @export
 use_roxygen_md <- function() {
@@ -17,15 +16,13 @@ use_roxygen_md <- function() {
     use_description_field("RoxygenNote", roxy_ver)
     ui_todo("Run {ui_code('devtools::document()')}")
   } else if (!uses_roxygen_md()) {
-    check_installed("roxygen2md")
+    use_description_field("Roxygen", "list(markdown = TRUE)")
+
     if (!uses_git()) {
       ui_todo("Use git to ensure that you don't lose any data")
     }
     ui_todo(
-      "
-      Refer to {ui_code('roxygen2md::roxygen2md()')} to use markdown markup \\
-      with roxygen2.
-      "
+      "Run {ui_code('roxygen2md::roxygen2md()')} to convert existing Rd markdown to RMarkdown"
     )
     ui_todo("Run {ui_code('devtools::document()')} when you're done.")
   }