Help: improved instructions to build binary distribution because the old instructions didn't seem to work on Windows

Author: joshtynjala

documentation/help/markdown/sdk/build-binary-distribution.md

@@ -25,7 +25,7 @@ The document explains how to build the Feathers SDK from a binary distribution.
 
     If you want to target a specific version of Flash Player and AIR, you may modify the command to specify the required versions:
 
-        ant -f installer.xml -Dflash.sdk.version=22.0 -Dair.sdk.version=22.0
+        ant -f installer.xml install -Dflash.sdk.version=22.0 -Dair.sdk.version=22.0
 
 1. When prompted to install each dependency, type `y` and press Enter.