Update cran-comments

Author: hadley

cran-comments.md

@@ -1,3 +1,11 @@
 ## R CMD check results
 
 0 errors | 0 warnings | 0 notes
+
+## revdepcheck results
+
+We checked 4 reverse dependencies, comparing R CMD check results across CRAN and dev versions of this package.
+
+ * We saw 1 new problem with the fr package, and we have provided a patch
+   at https://github.com/cole-brokamp/fr/pull/15
+ * We failed to check 0 packages