Add missing docs

Author: nyalldawson

python/core/locator/qgslocatorfilter.sip.in

@@ -211,6 +211,9 @@ custom configuration widget.
   signals:
 
     void finished();
+%Docstring
+Emitted when the filter finishes fetching results.
+%End
 
     void resultFetched( const QgsLocatorResult &result );
 %Docstring

src/core/locator/qgslocatorfilter.h

@@ -234,6 +234,9 @@ class CORE_EXPORT QgsLocatorFilter : public QObject
 
   signals:
 
+    /**
+     * Emitted when the filter finishes fetching results.
+     */
     void finished();
 
     /**