Update _index.md

Author: azarboon

content/en/docs/concepts/containers/_index.md

@@ -13,6 +13,8 @@ card:
 
 <!-- overview -->
 
+Note that "container" is an overloaded term. Whenever you use the word, check whether your audience uses the same definition.
+
 Each container that you run is repeatable; the standardization from having
 dependencies included means that you get the same behavior wherever you
 run it.