Update alertbox.adoc

Removed unneeded new line breaks.

src/docs/asciidoc/jme3/contributions/tonegodgui/alertbox.adoc

@@ -10,11 +10,11 @@ ifdef::env-github,env-browser[:outfilesuffix: .adoc]
 
 == AlertBox Class
 
-The AlertBox class extends Window, adding a scroll area for displaying messages, as well as a configurable button for closing the AlertBox.+
+The AlertBox class extends Window, adding a scroll area for displaying messages, as well as a configurable button for closing the AlertBox.
 
 It utilizes the 3 standard constructors as shown in the <<jme3/contributions/tonegodgui/quickstart#,Quick Start Guide>>.
 
-*Constructor 1:*+
+*Constructor 1:*
 
 [source,java]
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@@ -29,7 +29,7 @@ AlertBox alert = new AlertBox(screen, “alert”, new Vector2f(15, 15));
 
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-*Constructor 2:*+
+*Constructor 2:*
 
 [source,java]
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@@ -43,7 +43,7 @@ AlertBox alert = new AlertBox(screen, “alert”, new Vector2f(15, 15),
 
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-*Constructor 3:*+
+*Constructor 3:*
 
 [source,java]
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