fix links

docs/modules/core/pages/app/simpleapplication.adoc

@@ -115,8 +115,8 @@ a|Stops the running jME3 game and closes the jME3 window.
 a|start(Type.Headless) etc
 a|Switch Context com.​jme3.​system.​JmeContext.Type when starting the application: +
 Type.Display – jME application runs in a window of its own. (This is the default.) +
-Type.Canvas – jME application is embedded in a xref:jme3/advanced/swing_canvas.adoc[Swing Canvas]. +
-Type.Headless – jME application runs its event loop without calculating any view and without opening any window. Can be used for a xref:jme3/advanced/headless_server.adoc[Headless Server] application. +
+Type.Canvas – jME application is embedded in a xref:tutorials:how-to/java/swing_canvas.adoc[Swing Canvas]. +
+Type.Headless – jME application runs its event loop without calculating any view and without opening any window. Can be used for a xref:networking:headless_server.adoc[Headless Server] application. +
 Type.OffscreenSurface – jME application view is not shown and no window opens, but everything calculated and cached as bitmap (back buffer) for use by other applications.
 
 |===

docs/modules/core/pages/gui/nifty_gui.adoc

@@ -8,7 +8,7 @@
 image::gui/nifty-gui-13.png[nifty-gui-13.png,width="276",height="217",align="left"]
 
 
-You may want your players to press a button to save a game, you want a scrolling text field for highscores, a text label to display the score, drop-downs to select keymap preferences, or checkboxes to specify multi-media options. Usually you solve these tasks by using Swing controls. Although it is possible to embed a xref:jme3/advanced/swing_canvas.adoc[jME3 canvas] in a Swing +++<abbr title="Graphical User Interface">GUI</abbr>+++, a 3D game typically runs full-screen, or in a window of its own.
+You may want your players to press a button to save a game, you want a scrolling text field for highscores, a text label to display the score, drop-downs to select keymap preferences, or checkboxes to specify multi-media options. Usually you solve these tasks by using Swing controls. Although it is possible to embed a xref:tutorials:how-to/java/swing_canvas.adoc[jME3 canvas] in a Swing +++<abbr title="Graphical User Interface">GUI</abbr>+++, a 3D game typically runs full-screen, or in a window of its own.
 
 This document introduces you to link:https://github.com/nifty-gui/nifty-gui/[Nifty GUI], a Java library for building interactive graphical user interfaces (GUIs) for games or similar applications. Nifty +++<abbr title="Graphical User Interface">GUI</abbr>+++ (the `de.lessvoid.nifty` package) is well integrated with jME3 through the `com.jme3.niftygui` package. You define the base +++<abbr title="Graphical User Interface">GUI</abbr>+++ layout in XML, and control it dynamically from your Java code. The necessary JAR libraries are included in your jME3 download, you do not need to install anything extra. (Just make sure they are on the classpath.)
 

docs/modules/core/pages/util/sky.adoc

@@ -53,5 +53,5 @@ Box or Sphere?
 
 For more information on Skymap creation see:
 
-*  xref:jme3/advanced/free_skymaps.adoc[How to create free skymaps]
+*  xref:xref:tutorials:how-to/util/free_skymaps.adoc[How to create free skymaps]
 *  <<tutorials:how-to/modeling/blender/blender.adoc#skybox-baking,SkyBox baking>>

docs/modules/tutorials/nav.adoc

@@ -45,6 +45,7 @@
 ***** link:https://youtu.be/JzRe2Dxbcmc?list=PLv6qR9TGkz8RcUr-fOHI2SksWA4BAU9TS[Part 3- Import to JME]
 ***** link:https://youtu.be/8wwDRDJop7k?list=PLv6qR9TGkz8RcUr-fOHI2SksWA4BAU9TS[Part 4- Play Animation]
 ** xref:how-to/debugging.adoc[Debugging with Wireframes]
+** xref:how-to/util/free_skymaps.adoc[How to create free skymaps]
 ** Java Tips
 *** xref:how-to/java/localization.adoc[Localization]
 *** xref:how-to/java/swing_canvas.adoc[Swing Canvas]