R: fix command case and add examples (#4957)

pages/common/R.md

@@ -0,0 +1,32 @@
+# R
+
+> R language interpreter.
+> More information: <https://www.r-project.org>.
+
+- Start an R interactive shell (REPL):
+
+`R`
+
+- Check R version:
+
+`R --version`
+
+- Start R in vanilla mode (i.e. a blank session that doesn't save the workspace at the end):
+
+`R --vanilla`
+
+- Execute a file:
+
+`R -f {{path/to/file.R}}`
+
+- Execute an R expression and then exit:
+
+`R -e {{expr}}`
+
+- Run R with a debugger:
+
+`R -d {{debugger}}`
+
+- Check R packages from package sources:
+
+`R CMD check {{path/to/package_source}}`

pages/common/r.md

@@ -1,16 +0,0 @@
-# r
-
-> R language interpreter.
-> More information: <https://www.r-project.org>.
-
-- Start an R interactive shell (REPL):
-
-`R`
-
-- Check R version:
-
-`R --version`
-
-- Execute a file:
-
-`R -f {{file.R}}`