supplement copyright of GraphGym (#333)

LICENSE

@@ -516,4 +516,34 @@ Unless required by applicable law or agreed to in writing, software
 distributed under the License is distributed on an "AS IS" BASIS,
 WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 See the License for the specific language governing permissions and
-limitations under the License.
+limitations under the License.
+
+--------------------------------------------------------------------------------
+
+The registration mechanism for federatedscope/contrib/ and the code structure
+of federatedscope/core/configs/ are adapted from GraphGym:
+https://github.com/snap-stanford/GraphGym (MIT License)
+
+Copyright (c) 2021 Jiaxuan You
+Copyright (c) 2021 Jiaxuan You, Matthias Fey
+Copyright (c) 2020 Jiaxuan You, Rex Ying, Jonathan Gomes Selman
+Copyright (c) Facebook, Inc. and its affiliates.
+Additional copyrights are specified in relevant subdirectories.
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.