Fix typo.

doc/_posts/2013-12-12-capnproto-0.4-time-travel.md

@@ -7,7 +7,7 @@ author: kentonv
 Well, [Hofstadter](http://en.wikipedia.org/wiki/Hofstadter's_law) kicked in and this release took
 way too long.  But, after three long months, I'm happy to announce:
 
-### Time-Traveling RPC
+### Time-Traveling RPC _(Promise Pipelining)_
 
 <img src='{{ site.baseurl }}images/time-travel.png' style='max-width:639px'>
 

doc/rpc.md

@@ -164,7 +164,7 @@ similarly-naive protocols that lack promise pipelining.  Promise pipelining is t
 
 ### Security
 
-Cap'n Proto interafce references are
+Cap'n Proto interface references are
 [capabilities](http://en.wikipedia.org/wiki/Capability-based_security).  That is, they both
 designate an object to call and confer permission to call it.  When a new object is created, only
 the creator is initially able to call it.  When the object is passed over a network connection,