Auto merge of #3392 - matklad:patch-1, r=steveklabnik
authorbors <bors@rust-lang.org>
Mon, 12 Dec 2016 19:24:38 +0000 (19:24 +0000)
committerbors <bors@rust-lang.org>
Mon, 12 Dec 2016 19:24:38 +0000 (19:24 +0000)
Add explanatory comment to header.html

See #3387


Trivial merge