Merge pull request #1413 from adewale/patch-2

Tidied up last reference to click-to-play rather than placeholder

extensions/amp-iframe/amp-iframe.md

@@ -20,7 +20,7 @@ Displays an iframe.
 
 `amp-iframe` has several important differences from vanilla iframes that are designed to make it more secure and avoid AMP files that are dominated by a single iframe:
 
-- `amp-iframe` may not appear close to the top of the document (except for `click-to-play` iframes as described below). They must be either 600px away from the top or not within the first 75% of the viewport when scrolled to the top – whichever is smaller. NOTE: We are currently looking for feedback as to how well this restriction works in practice.
+- `amp-iframe` may not appear close to the top of the document (except for iframes that use `placeholder` as described below). They must be either 600px away from the top or not within the first 75% of the viewport when scrolled to the top – whichever is smaller. NOTE: We are currently looking for feedback as to how well this restriction works in practice.
 - They are sandboxed by default. [Details](#sandbox)
 - They must only request resources via HTTPS or from a data-URI or via the srcdoc attribute.
 - They must not be in the same origin as the container unless they do not allow `allow-same-origin` in the sandbox attribute.