The editing-help page does not mention the simplest types of links:
Here's a really simple link to [Google]. [google]: http://www.google.com/
Are these types of links deliberately discouraged for some reason, or was it an oversight?
There are three ways to write links. Each is easier to read than the last:
Here's an inline link to [Google](http://www.google.com/). Here's a reference-style link to [Google]. Here's a very readable link to [Yahoo!][yahoo]. : http://www.google.com/ [yahoo]: http://www.yahoo.com/
The link definitions can appear anywhere in the document -- before or after the place where you use them. The link definition names  and [yahoo] can be any unique string, and are case-insensitive; [yahoo] is the same as [YAHOO].