Update base.fs.upload docs to reflect exceptions thrown

fs/base.py

@@ -1308,6 +1308,10 @@ def upload(self, path, file, chunk_size=None, **options):
                 sensible default.
             **options: Implementation specific options required to open
                 the source file.
+
+        Raises:
+            fs.errors.ResourceNotFound: If a parent directory of
+                ``path`` does not exist.
 
         Note that the file object ``file`` will *not* be closed by this
         method. Take care to close it after this method completes

fs/test.py

@@ -1494,6 +1494,10 @@ def test_upload(self):
         with self.fs.open("foo", "rb") as f:
             data = f.read()
         self.assertEqual(data, b"bar")
+
+        # upload to non-existing path (/foo/bar)
+        with self.assertRaises(errors.ResourceNotFound):
+            self.fs.upload("/foo/bar/baz", bytes_file)
 
     def test_upload_chunk_size(self):
         test_data = b"bar" * 128