Drop chalkboard from demos

currently blurs the screen :))

Change-Id: Ibd3d314b2abc0a1d7ae3563f748cfde7e70d916d
diff --git a/examples/ids.Rmd b/examples/ids.Rmd
index 7323426..0b7762a 100644
--- a/examples/ids.Rmd
+++ b/examples/ids.Rmd
@@ -10,7 +10,6 @@
       - search
       - zoom
       - notes
-      - chalkboard
       - menu
     reveal_options:
       chalkboard:
diff --git a/examples/simple.Rmd b/examples/simple.Rmd
index 035e391..3ab2404 100644
--- a/examples/simple.Rmd
+++ b/examples/simple.Rmd
@@ -7,7 +7,6 @@
       - search
       - zoom
       - notes
-      - chalkboard
       - menu
     reveal_options:
       chalkboard: