Remove invalid doxygen note

It's only flipping a bool, and possibly in some circumstances
it's more efficient to add features one by one rather than storing
large number of features in a temporary list

python/core/qgsvectorlayer.sip

@@ -903,16 +903,6 @@ Return the provider type for this layer
 
     virtual bool addFeature( QgsFeature &feature );
 
-%Docstring
- Adds a single ``feature`` to the layer.
- Calling this method causes the layer to recalculate it's extents, which can be
- expensive. If multiple features are to be added to the layer then it is more
- efficient to call addFeatures(), as addFeatures() will only trigger a single
- layer extent recalculation.
- \see addFeatures()
- :return: true in case of success and false in case of failure
- :rtype: bool
-%End
 
     bool updateFeature( QgsFeature &f );
 %Docstring

src/core/qgsvectorlayer.h

@@ -872,15 +872,6 @@ class CORE_EXPORT QgsVectorLayer : public QgsMapLayer, public QgsExpressionConte
       return getFeatures( QgsFeatureRequest( rectangle ) );
     }
 
-    /**
-     * Adds a single \a feature to the layer.
-     * Calling this method causes the layer to recalculate it's extents, which can be
-     * expensive. If multiple features are to be added to the layer then it is more
-     * efficient to call addFeatures(), as addFeatures() will only trigger a single
-     * layer extent recalculation.
-     * \see addFeatures()
-     * \returns true in case of success and false in case of failure
-     */
     bool addFeature( QgsFeature &feature ) override;
 
     /** Updates an existing feature. This method needs to query the datasource