README: update license section

It's no longer true that libplacebo derives from mpv/mplayer.

LICENSE

@@ -1,24 +1,3 @@
-libplacebo's code base is heavily derived from mpv, which is a fork of mplayer2,
-which is a fork of MPlayer. Currently, this includes files inside the following
-directories:
-
-  subprojects/bstr/*
-  subprojects/xtalloc/*
-
-All of the affected MPlayer/mplayer2/mpv code has been successfully relicensed
-to LGPLv2.1+; which means that libplacebo as a whole is licensed under the GNU
-Lesser General Public License version 2.1 or later. All new contributions must
-be published under the same license.
-
-Note to contributors: This project will remain LGPLv2.1+, so any new code that
-is ported from mpv (or other sources) must be LGPLv2.1+ compatible, i.e.
-porting GPL, LGPLv2 (without the "or later") or LGPLv3+ code is not allowed
-and must be rewritten instead.
-
-Appended is a complete copy of the LGPLv2.1 license text.
-
--------------------------------------------------------------------------------
-
                   GNU LESSER GENERAL PUBLIC LICENSE
                        Version 2.1, February 1999
 

README.md

@@ -214,12 +214,11 @@ Support this project by becoming a sponsor. Your logo will show up here with a l
 
 ### License
 
-Since the code derives from several LGPLv2.1+-licensed parts of mpv, there's
-little choice but to license libplacebo the same way. It's worth pointing out
-that, except for some minor exceptions (e.g. filters.c and colorspace.c), most
-of the code is either original work or can be attributed to only a small
-number of developers, so a relicensing to a more permissive license might be
-possible in principle.
+libplacebo is currently available under the terms of the LGPLv2.1 (or later)
+license. However, it's possible to release it under a more permissive license
+(e.g. BSD2) if a use case emerges.
+
+Please open an issue if you have a use case for a BSD2-licensed libplacebo.
 
 ## Installing