Bump version for release

Author: jimhester

DESCRIPTION

@@ -1,6 +1,6 @@
 Package: devtools
 Title: Tools to Make Developing R Packages Easier
-Version: 2.3.0.9000
+Version: 2.3.1
 Authors@R: 
     c(person(given = "Hadley",
              family = "Wickham",

NEWS.md

@@ -1,9 +1,11 @@
-# devtools (development version)
+# devtools 2.3.1
 
 * `run_examples()` arguments `run` and `test` are deprecated in favor of the (hopefully) more clear `run_dontrun` and `run_donttest` (pkgload/#107).
 
 * Previously deprecated functions `dr_devtools()` and `dr_github()` have been removed.
 
+* Documentation has been synced with remotes 2.2.0
+
 # devtools 2.3.0
 
 * `build()` now errors with a more informative error message when passed an