Fix typo

Change-Id: I351a41c7b6964bdf60d9231640c18461fca81ff2
Reviewed-on: https://gerrit.libreoffice.org/73575
Tested-by: Jenkins
Reviewed-by: Julien Nabet <serval2412@yahoo.fr>

forms/source/component/refvaluecomponent.hxx

@@ -27,7 +27,7 @@
 namespace frm
 {
 
-    /** a OBoundControlModel which features the exchange of a reference value
+    /** an OBoundControlModel which features the exchange of a reference value
     */
     class OReferenceValueComponent : public OBoundControlModel
     {