Add LICENCE and update README.md

Author: pmor

LICENCE

@@ -0,0 +1,21 @@
+MIT License
+
+Copyright (c) 2020 Pedro Moreira
+
+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.

README.md

@@ -2,7 +2,7 @@
 
 Add binaries for image-optim on Heroku, can be used with heroku-buildpack-multi.
 
-Built-in support for [image-optim](https://github.com/toy/image_optim) gem, creation of `.image-optim.yml` config file. 
+Built-in support for [image-optim](https://github.com/toy/image_optim) gem, creation of `.image-optim.yml` config file.
 
 Binaries in this buildpacks :
 
@@ -27,4 +27,10 @@ On compilation :
 - Add config file .image-optim.yml if Gemfile present
 - Version of each binaries is displayed
 
+## Credits
 
+© 2020 Pedro Moreira
+
+Forked from https://github.com/bobbus/image-optim-buildpack
+
+Released under the MIT License.