added clarification on directives/blocks

docs/docsite/rst/playbooks_blocks.rst

@@ -4,7 +4,8 @@ Blocks
 In 2.0 we added a block feature to allow for logical grouping of tasks and even
 in play error handling. Most of what you can apply to a single task can be applied
 at the block level, which also makes it much easier to set data or directives common
-to the tasks.
+to the tasks. This does not mean the directive affects the block itself, but is inherited
+by the tasks enclosed by a block. i.e. a `when` will be applied to the tasks, not the block itself.
 
 
 .. code-block:: YAML