Fixed #8463: added missing reference to bztar in shutil's documentation.
diff --git a/Lib/shutil.py b/Lib/shutil.py
index a94c5e1..5cfea63 100644
--- a/Lib/shutil.py
+++ b/Lib/shutil.py
@@ -525,7 +525,7 @@
'base_name' is the name of the file to create, minus any format-specific
extension; 'format' is the archive format: one of "zip", "tar", "ztar",
- or "gztar".
+ "bztar" or "gztar".
'root_dir' is a directory that will be the root directory of the
archive; ie. we typically chdir into 'root_dir' before creating the