extract: document lack of wildcard support in default pattern style

docs/usage/extract.rst

@@ -19,6 +19,9 @@ Examples
     # Extract the "src" directory but exclude object files
     $ borg extract my-files home/USERNAME/src --exclude '*.o'
 
+    # Extract only the object files
+    $ borg extract my-files 'sh:home/USERNAME/src/*.o'
+
     # Restore a raw device (must not be active/in use/mounted at that time)
     $ borg extract --stdout my-sdx | dd of=/dev/sdx bs=10M
 

src/borg/archiver/extract_cmd.py

@@ -130,6 +130,10 @@ def build_parser_extract(self, subparsers, common_parser, mid_common_parser):
             When parent directories are not extracted (because of using file/directory selection
             or any other reason), borg can not restore parent directories' metadata, e.g. owner,
             group, permission, etc.
+
+            The default interpretation for the paths to extract is `pp:` which is a literal
+            path-prefix match. If you want to use e.g. a wildcard, you must select a different
+            pattern style such as `sh:` or `fm:`. See :ref:`borg_patterns` for more information.
         """
         )
         subparser = subparsers.add_parser(