Add 'LICENSE'. Update 'README.md'

LICENSE

@@ -0,0 +1,43 @@
+Spelunky® User License v1.1b
+Copyright (c) 2008, 2009 Derek Yu and Mossmouth, LLC
+Last Updated on December 25th, 2009
+
+1. Preamble
+
+As of December 25th, 2009, I'm releasing the .gmk files for Spelunky and the Spelunky configuration program to the public.  The game and the source code are being provided to you for the purpose of learning, entertainment, and sharing with the Spelunky community.
+
+I'm interested in seeing what you guys create!  Happy Spelunky-ing!
+
+2. Definitions
+
+"Mossmouth" is defined as Derek Yu and Mossmouth, LLC.
+
+The "Game" is defined as the Spelunky game, its program, and all related files, including, but not limited to, the Spelunky configuration program.
+
+The "Source Code" is defined as the .gmk files for Spelunky and the Spelunky configuration program, and all of the objects, scripts, sprites, and tiles contained within those files.
+
+"Covered Works" are defined as the Game, the Source Code, and any modified versions of the Game and the Source Code.
+
+3. Rights Granted
+
+The rights granted under this license are granted for the duration of the copyright.
+
+You may modify and redistribute the Game and its Source Code under the following conditions:
+
+  (1) This license and any appropriate copyright notices in the Source Code are kept intact.
+
+  (2) You may not sell Covered Works.
+
+  (3) You must display an appropriate copyright notice somewhere in the beginning of all Covered Works and in any documentation accompanying such Covered Works.
+
+  (4) If you share a modified version of either the Game or its Source Code with others, you must not present it as an unmodified, or official, version of the Game or the Source code.  Please make it apparent that it is a mod.
+
+By accepting this license you are agreeing not to restrict or prevent Mossmouth from modifying or adding to Spelunky in any way.
+
+4. Disclaimer of Warranty
+
+The Game and its Source Code are provided WITHOUT WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+
+5. Limitation of Liability
+
+In no event, unless required by applicable law or agreed to in writing will any copyright holders be liable to you for damages, including any general, special, incidental, or consequential damages arising out of the use or inability to use the Game, the Source Code, or modified versions of the Game or the Source Code, even if such holder has been advised of the possibility of such damages.  Such damages include, but are not limited to, loss of data or data being rendered inaccurate.

README.md

@@ -4,7 +4,7 @@ A game by [Derek Yu](http://www.mossmouth.com/)
 Ported from **GameMaker 8.1** to **GameMaker Studio** by [Darius Kazemi](http://tinysubversions.com/2012/07/spelunky-html5/) and [YoYo Games](https://www.yoyogames.com/) (as far as I can tell).
 
 Source code was published in **Humble Weekly Bundle: Play and Create with GameMaker**.
-According to [Spelunky User License](https://github.com/yancharkin/SpelunkyClassicHD/blob/master/help.rtf) it's totally legal to distribute source code and binaries. If I'm wrong let me know.
+According to [Spelunky User License](https://github.com/yancharkin/SpelunkyClassicHD/blob/master/LICENSE) it's totally legal to distribute source code and binaries. If I'm wrong let me know.
 
 ## Things I have implemented:
 - Support for different aspect ratios (originally 4:3 only)