Fixed #8463: added missing reference to bztar in shutil's documentation.
diff --git a/Doc/library/shutil.rst b/Doc/library/shutil.rst
index 25c911f..23f03e7 100644
--- a/Doc/library/shutil.rst
+++ b/Doc/library/shutil.rst
@@ -249,7 +249,7 @@
*base_name* is the name of the file to create, including the path, minus
any format-specific extension. *format* is the archive format: one of
- "zip", "tar", "ztar", or "gztar".
+ "zip", "tar", "ztar", "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