Add a link to attendee notes and info doc

This should be useful in case meet.kernel.social goes down at just
the wrong moment, for example.

Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Change-Id: I33f9eb12ba756c7169396b6d39a0dd22922264d8
diff --git a/index.md b/index.md
index 051fa02..90802e3 100644
--- a/index.md
+++ b/index.md
@@ -99,6 +99,14 @@
 
 ## During the Summit
 
+### Notes and logistics
+
+The [attendee notes and
+info](https://docs.google.com/document/d/1g_QapVhHejHorpUzzjpT5DlPi6ovNlEK4423uYWypbU/edit)
+document has the password for attending the summit, break-out room
+assignments, and other information that may be useful during the
+event.  In case of technical difficulties, check that doc first.
+
 ### Schedule
 
 #### Monday, September 14th