Fix faulty cheat sheet editor ID constant

The constant does not match the actual editor ID (misses a dot).

Author: HeikoKlare

ua/org.eclipse.pde.ua.ui/src/org/eclipse/pde/internal/ua/ui/IConstants.java

@@ -19,7 +19,7 @@ public interface IConstants {
 	public static final String COMPOSITE_CHEAT_SHEET_EDITOR_ID = PDEUserAssistanceUIPlugin.PLUGIN_ID
 			+ ".compositeCheatSheetEditor"; //$NON-NLS-1$
 	public static final String SIMPLE_CHEAT_SHEET_EDITOR_ID = PDEUserAssistanceUIPlugin.PLUGIN_ID
-			+ "simpleCheatSheetEditor"; //$NON-NLS-1$
+			+ ".simpleCheatSheetEditor"; //$NON-NLS-1$
 	public static final String CONTEXT_HELP_EDITOR_ID = PDEUserAssistanceUIPlugin.PLUGIN_ID
 			+ ".ctxHelpEditor"; //$NON-NLS-1$
 	public static final String TABLE_OF_CONTENTS_EDITOR_ID = PDEUserAssistanceUIPlugin.PLUGIN_ID