Add slides for Community Retrospective talk

Signed-off-by: Edwin Kempin <ekempin@google.com>
Change-Id: Id0fcc4920afdbbbb7188cab091d8c7b33f173b11
diff --git a/sessions/community-retrospective.md b/sessions/community-retrospective.md
index 9450397..13d16da 100644
--- a/sessions/community-retrospective.md
+++ b/sessions/community-retrospective.md
@@ -14,4 +14,6 @@
 To take part in the brainstorming participants need a notebook with a browser
 and a connection to the internet.
 
+[Presentation slides](https://docs.google.com/presentation/d/1ScU706bYqCEZMU4z3EBHzhj6CQ12ftNo847mzzbMOVU/edit?usp=sharing)
+
 *[Edwin Kempin, Google](../speakers.md#ekempin)*