update docs, add streaming library to checklist

USAGE.md

@@ -160,8 +160,14 @@ Usage of ./bin/samcatd:
 
 example config - valid for both ephsite and samcat
 ==================================================
+Options are still being added, pretty much as fast as I can put them
+in. For up-to-the-minute options, see [the checklist](config/CHECKLIST.md)
 
-(ephsite will only use top-level options)
+(ephsite will only use top-level options, but they can be labeled or
+unlabeled)
+(samcatd treats the first set of options it sees as the default, and
+does not start tunnels based on unlabeled options unless passed the
+-s flag.)
 
 ```