LEGAL: add entries for non-MIT licensed files.

LEGAL

@@ -3,3 +3,38 @@ LEGAL NOTICE INFORMATION
 
 All the files in this distribution are covered under the MIT license
 (see the file LICENSE) except some files mentioned below:
+
+- src/readfloat.c: public domain by Yasuhiro Matsumoto (@mattn)
+- src/fmt_fp.c: public domain by Dave Hylands (@dhylands)
+- mrbgems/mruby-dir/src/Win/dirent.c: MIT-like license by Kevlin Henney
+
+[src/readfloat.c]
+
+strtod implementation.
+author: Yasuhiro Matsumoto (@mattn)
+license: public domain
+
+The original code can be found in https://github.com/mattn/strtod
+
+[src/fmt_fp.c]
+
+The code in this function was inspired from Fred Bayer's pdouble.c.
+Since pdouble.c was released as Public Domain, I'm releasing this
+code as public domain as well.
+
+Dave Hylands
+
+The original code can be found in https://github.com/dhylands/format-float
+
+[mrbgems/mruby-dir/src/Win/dirent.c] used only for Windows platform
+
+Copyright Kevlin Henney, 1997, 2003, 2012. All rights reserved.
+
+Permission to use, copy, modify, and distribute this software and its
+documentation for any purpose is hereby granted without fee, provided
+that this copyright and permissions notice appear in all copies and
+derivatives.
+
+This software is supplied "as is" without express or implied warranty.
+
+But that said, if there are any problems please get in touch.