update LICENSE file to include ed25519 license

LICENSE

@@ -81,3 +81,24 @@ SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
 FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
 ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
 DEALINGS IN THE SOFTWARE.
+
+------------------------------------------------------------------------------
+
+ed25519 implementation based on:
+
+Copyright (c) 2015 Orson Peters <orsonpeters@gmail.com>
+
+This software is provided 'as-is', without any express or implied warranty. In no event will the
+authors be held liable for any damages arising from the use of this software.
+
+Permission is granted to anyone to use this software for any purpose, including commercial
+applications, and to alter it and redistribute it freely, subject to the following restrictions:
+
+1. The origin of this software must not be misrepresented; you must not claim that you wrote the
+   original software. If you use this software in a product, an acknowledgment in the product
+   documentation would be appreciated but is not required.
+
+2. Altered source versions must be plainly marked as such, and must not be misrepresented as
+   being the original software.
+
+3. This notice may not be removed or altered from any source distribution.

ed25519/license.txt

@@ -0,0 +1,16 @@
+Copyright (c) 2015 Orson Peters <orsonpeters@gmail.com>
+
+This software is provided 'as-is', without any express or implied warranty. In no event will the
+authors be held liable for any damages arising from the use of this software.
+
+Permission is granted to anyone to use this software for any purpose, including commercial
+applications, and to alter it and redistribute it freely, subject to the following restrictions:
+
+1. The origin of this software must not be misrepresented; you must not claim that you wrote the
+   original software. If you use this software in a product, an acknowledgment in the product
+   documentation would be appreciated but is not required.
+
+2. Altered source versions must be plainly marked as such, and must not be misrepresented as
+   being the original software.
+
+3. This notice may not be removed or altered from any source distribution.

ed25519/readme.md

@@ -162,4 +162,4 @@ ed25519_key_exchange(shared_secret, other_public_key, private_key);
 
 License
 -------
-All code is in the public domain.
+All code is released under the zlib license. See license.txt for details.