Add LICENSE: research-use grant + commercial-licence requirement + AS-IS

- Section 2: research-only use granted royalty-free.
  - Section 3: commercial use requires a separate written licence
    (contact licensing@sevana.biz).
  - Sections 4-5: full AS IS disclaimer + zero-dollar liability cap.
  - Section 6: automatic termination on breach.
  - Section 8: attribution requirement for academic publications.

README.md updated with a one-paragraph summary that points to
LICENSE for full text.

README.md

@@ -128,7 +128,19 @@ fall back.
 
 ## Licence
 
-Proprietary.  Internal use only.
+The Software is licensed under the terms contained in the [LICENSE](./LICENSE)
+file in this repository.
+
+In short:
+- **Research and non-commercial use**: granted free of charge under
+  the conditions in section 2 of the LICENSE.
+- **Commercial use**: requires a separate written commercial
+  licence from the Licensor.  Contact `licensing@sevana.biz`.
+- **No warranty**: the Software is provided strictly "AS IS",
+  without warranty of any kind.  The Licensor's total aggregate
+  liability is limited to zero.
+
+Please read the LICENSE file in full before using the Software.
 
 ## Support