Drop outdated RELEASE_NOTES

A new RELEASE_NOTES specific to the release will be added.

RELEASE_NOTES

- ┌────────────────────────────────────────┐
- │ RELEASE NOTES for FFmpeg 2.5 "Bohr"    │
- └────────────────────────────────────────┘
-
-   The FFmpeg Project proudly presents FFmpeg 2.5 "Bohr", just 2.5 months
-   after the release of 2.4. Since this wasn't a long time ago, the Changelog
-   is a bit short this time.
-
-   As usual, if you have any question on this release or any FFmpeg related
-   topic, feel free to join us on the #ffmpeg IRC channel (on
-   irc.freenode.net).
-
-   ┌────────────────────────────┐
-   │ 🔨  API Information         │
-   └────────────────────────────┘
-
-     FFmpeg 2.5 includes the following library versions:
-
-       • libavutil      54.15.100
-       • libavcodec     56.13.100
-       • libavformat    56.15.102
-       • libavdevice    56. 3.100
-       • libavfilter     5. 2.103
-       • libswscale      3. 1.101
-       • libswresample   1. 1.100
-       • libpostproc    53. 3.100
-
-     Important API changes since 2.4:
-
-       • avpriv_dv_frame_profile2() has been deprecated
-
-
-     Please refer to the doc/APIchanges file for more information.
-
- ┌────────────────────────────┐
- │ ★  List of New Features    │
- └────────────────────────────┘
-
-   ┌────────────────────────────┐
-   │ ffprobe                    │
-   └────────────────────────────┘
-
-    • -show_pixel_formats option
-
-   ┌────────────────────────────┐
-   │ ffserver                   │
-   └────────────────────────────┘
-
-    • codec private options support
-
-   ┌────────────────────────────┐
-   │ libavcodec                 │
-   └────────────────────────────┘
-
-    • STL subtitle decoder
-    • libutvideo YUV 4:2:2 10bit support
-    • animated WebP decoding support
-    • zygoaudio decoding support
-
-   ┌────────────────────────────┐
-   │ libavdevice                │
-   └────────────────────────────┘
-
-    • XCB-based screen-grabber
-    • AVFoundation screen capturing support
-
-   ┌────────────────────────────┐
-   │ libavformat                │
-   └────────────────────────────┘
-
-    • HEVC/H.265 RTP payload format (draft v6) packetizer
-    • SUP/PGS subtitle demuxer
-    • STL subtitle demuxer
-    • UDP-Lite support (RFC 3828)
-    • creating DASH compatible fragmented MP4, MPEG-DASH segmenting muxer
-    • WebP muxer
-    • APNG demuxer
-
-   ┌────────────────────────────┐
-   │ libavfilter                │
-   └────────────────────────────┘
-
-    • xBR scaling filter
-
-   ┌────────────────────────────┐
-   │ libavutil                  │
-   └────────────────────────────┘
-
-    • CAST128 symmetric block cipher, ECB mode
-
-   ┌────────────────────────────┐
-   │ libpostproc                │
-   └────────────────────────────┘
-
-    • visualization support
-
- ┌────────────────────────────┐
- │ ⚠  Behaviour changes       │
- └────────────────────────────┘
-    • XMP metadata is not exported by default anymore as it can be huge.
-      see the export_xmp option