doc: fixed processing's description for v.extract (#3637)

Author: lynxlynxlynx

python/plugins/processing/algs/grass/description/v.extract.txt

@@ -1,5 +1,5 @@
 v.extract
-Selects vector objects from a vector layer a new layer containing only the selected objects.
+Selects vector objects from a vector layer and creates a new layer containing only the selected objects.
 Vector (v.*)
 ParameterVector|input|Vector layer|-1|False
 ParameterString|where|WHERE conditions of SQL statement without 'where' keyword|

python/plugins/processing/algs/grass7/description/v.extract.txt

@@ -1,5 +1,5 @@
 v.extract
-Selects vector objects from a vector layer a new layer containing only the selected objects.
+Selects vector objects from a vector layer and creates a new layer containing only the selected objects.
 Vector (v.*)
 ParameterVector|input|Vector layer|-1|False
 ParameterString|where|WHERE conditions of SQL statement without 'where' keyword|