Update file_types.adoc

Tweaked the first table to 10, 65, 25 to give as much space as possible to center column. Should need no more changes.

src/docs/asciidoc/jme3/intermediate/file_types.adoc

@@ -9,7 +9,7 @@ ifdef::env-github,env-browser[:outfilesuffix: .adoc]
 
 
 == jMonkeyEngine3 File Formats
-[cols="20,50,30", options="header"]
+[cols="10,65,25", options="header"]
 |===
 
 a|Suffix