vedit: add Vedit_extend_lines

git-svn-id: https://svn.osgeo.org/grass/grass/trunk@70713 15284696-431f-4ddb-bdfa-cd5b030d7da7

lib/vector/vedit/veditlib.dox

@@ -20,6 +20,8 @@ The library is used by <tt>v.edit</tt> module and wxGUI %vector digitizer.
 
  - Vedit_connect_lines()
 
+ - Vedit_extend_lines()
+
  - Vedit_chtype_lines()
 
  - Vedit_delete_lines()