Update jme3.adoc

Fixed link to SDK download.

src/docs/asciidoc/jme3.adoc

@@ -12,8 +12,7 @@ ifdef::env-github,env-browser[:outfilesuffix: .adoc]
 *  <<bsd_license#,Use jMonkeyEngine 3 for free under the BSD License>>
 *  <<jme3/requirements#,Software and hardware requirements>>
 *  <<jme3/features#,All Supported Features>>
-*  <</#Installation,Download jMonkeyEngine 3 SDK>>
-
+*  link:https://github.com/jMonkeyEngine/sdk#jmonkeyengine-software-development-kit-sdk-[Download jMonkeyEngine 3 SDK]
 
 == SDK Documentation