MAGETWO-50156: Create Issue Template for public GitHub

Author: ishakhsuvarov

ISSUE_TEMPLATE.md

@@ -0,0 +1,16 @@
+Steps to reproduce
+--
+1. Install Magento from `develop` branch.
+2. [Example] Add Configurable Product to the cart.
+3. ...
+
+Expected result
+--
+1. [Example] Configurable product added to the shopping cart.
+2. ...
+
+Actual result
+--
+1. [Example] Error message appears: "Cannot save quote".
+2. [Screenshot, logs]
+3. ...