Add https://github.com/o2r-project/containerit

ReproducibleResearch.md

@@ -223,6 +223,9 @@ restores the package setup on a different machine.
 - `r pkg("checkpoint")`: Allows you to install packages as
   they existed on CRAN on a specific snapshot date as if you had a
   CRAN time machine.
+- `r github("o2r-project/containerit")` (GitHub only): Package R sessions,
+    scripts, workspace directories, and R Markdown documents together with all
+    dependencies to execute them in Docker containers.
 - `r pkg("dateback")`: Works like a virtual CRAN snapshot for source packages.
   It automatically downloads and installs 'tar.gz' files with dependencies, all
   of which were available on a specific day.