Reword intro to Api Overview to flow better

Not sure if this is too dramatic. This is an attempt to address Issue #34, i.e. that "document set" was a bit unnatural. 

Decided to give a short sharp answer in the beginning, and tack on that initial sentence to the end of this section, which felt more natural as the preceding sentences explained the why behind it nicely.

api-overview/about-overview.md

@@ -2,11 +2,13 @@
 
 ### When Do I Need an Overview?
 
-Every document set should include an overview. This document tells potential users or buyers of the product the things they might want to know before adoption.
+Always.
+
+This document tells potential users or buyers of the product the things they might want to know before adoption.
 
 Many users install or plug into your service immediately because they are already familiar with it or someone else has decided that the team will use this solution. All of those people will go to your Quickstart, or will just get to work.
 
-There are other groups, however, who need to assess your product in order to decide whether they want to use it. They are either the managers responsible for a business decision, or they are engineers who don't know enough about your product to decide whether it can accomplish what they want it to do. People who fall in either of these groups might decide not adopt your product unless you provide an overview that answers their questions.  
+There are other groups, however, who need to assess your product in order to decide whether they want to use it. They are either the managers responsible for a business decision, or they are engineers who don't know enough about your product to decide whether it can accomplish what they want it to do. People who fall in either of these groups might decide to not adopt your product unless you provide an overview that answers their questions. As such your API documentation should always include an overview document. 
 
 ## Content of Your Overview