update README to include old and upcoming versions

Author: cwickham

README.md

@@ -1,6 +1,19 @@
 # A purrr tutorial
 
-This repo currently contains the contents of the tutorial from rstudio::conf "Happy R users purrr"
+This repo hosts the materials for a [purrr](http://purrr.tidyverse.org/) tutorial.
+
+## Upcoming in-person tutorials
+
+* [Cascadia R Conf](https://cascadiarconf.com/) Portland, OR, June 3 2017
+* [useR!](https://user2017.brussels/) Brussels, Belgium, July 4 2017
+* [London R-ladies](https://www.meetup.com/rladies-london/) London, U.K., July 12 2017 
+
+Older versions of the materials, from prior in-person tutorials, are also available:
+
+* [rstudio::conf Jan 2017 (2.25 hours)](https://github.com/cwickham/purrr-tutorial/tree/v0.1)
+
+
+
 
 ## Abstract