removed blank o16n notebooks

Former-commit-id: 4bbb04afad
2020-02-12 10:11:08 +00:00 · 2020-02-12 10:11:08 +00:00 · b075f8a19b
--- a/examples/05_operationalize/lightgbm_retail_o16n.ipynb
+++ b/examples/05_operationalize/lightgbm_retail_o16n.ipynb
--- a/examples/05_operationalize/placeholder.txt
+++ b/examples/05_operationalize/placeholder.txt
@ -0,0 +1 @@
+tbd