Update of mmap_mode description (#1203)

Co-authored-by: Olivier Grisel <[email protected]>

joblib/parallel.py

@@ -513,9 +513,11 @@ class Parallel(Logger):
  in Bytes, or a human-readable string, e.g., '1M' for 1 megabyte.
  Use None to disable memmapping of large arrays.
  Only active when backend="loky" or "multiprocessing".
- mmap_mode: {None, 'r+', 'r', 'w+', 'c'}
- Memmapping mode for numpy arrays passed to workers.
- See 'max_nbytes' parameter documentation for more details.
+ mmap_mode: {None, 'r+', 'r', 'w+', 'c'}, default: 'r'
+ Memmapping mode for numpy arrays passed to workers. None will 
+ disable memmapping, other modes defined in the numpy.memmap doc:
+ https://numpy.org/doc/stable/reference/generated/numpy.memmap.html
+ Also, see 'max_nbytes' parameter documentation for more details.
 
  Notes
  -----