Add some reading material

Two articles suggested by Kim Tran (thanks!).

Change-Id: I04e171a186af9d176518c6880c2386c803b22cfa
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
diff --git a/index.md b/index.md
index fe4e786..f18b522 100644
--- a/index.md
+++ b/index.md
@@ -42,8 +42,18 @@
 
 ## Resources
 
-We're providing pre-reading material (check back soon) on a range of
-topics.
+### Pre-summit
+
+We're providing pre-reading material on a range of topics. This list
+will grow over time --- check back soon.
+
+- Kapor Center's [tech leavers
+  study](https://www.kaporcenter.org/wp-content/uploads/2017/08/TechLeavers2017.pdf):
+  Why people voluntarily left jobs in tech
+- ZDNet's Alison DeNisco-Rayome on [Transgender employees in
+  tech](https://www.zdnet.com/article/transgender-employees-in-tech-why-this-progressive-industry-has-more-work-to-do-to-achieve-true-gender-inclusivity/)
+
+### Post-summit
 
 Bookmark this page to check back for a recap on the initial September
 event.