Fix asset licensing notices (#11468)

assets/icons/flags/LICENSE

@@ -0,0 +1,21 @@
+MIT License
+
+Copyright (c) 2020 @catamphetamine <purecatamphetamine@gmail.com>
+
+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.

assets/icons/flags/README.md

@@ -1,4 +1,9 @@
+**Rights holder: @catamphetamine.**
+
 The flags in this directory are from the excellent [country-flag-icons](https://gitlab.com/catamphetamine/country-flag-icons).
 
-MIT License
 Copyright (c) 2020 @catamphetamine <purecatamphetamine@gmail.com>
+
+**You may redistribute these files under country-flag-icons' MIT license, which is separate from Bluesky's repository license.** The complete license is in [`LICENSE`](./LICENSE) and must travel with redistributed copies.
+
+See [`ASSETS.md`](../../../ASSETS.md#6-third-party-assets-you-may-redistribute) for the full asset licensing picture.