Add README

Signed-off-by: Masanori Ogino <mogino@acm.org>

README.md

@@ -0,0 +1,37 @@
+<!-- SPDX-License-Identifier: MIT
+  --
+  -- Copyright (c) 2023  Masanori Ogino
+  --
+  -- 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.
+  -->
+
+# SJ3
+
+## Summary
+
+SJ3 is a kana-kanji conversion system for Japanese text input.
+
+## License
+
+Unless otherwise noted, SJ3 is released under the MIT License.
+
+## Acknowledgments
+
+We highly appreciate the release of SJ3 source code as a free and open source
+software by Sony Corporation.