avformat/rcwtenc: remove repeated documentation

The high level summary of RCWT can be delegated doc/muxers, which
makes it easier to maintain and more consistent with the documentation
of the demuxer.

Signed-off-by: Marth64 <marth64@proxyid.net>

libavformat/rcwtenc.c

@@ -21,11 +21,6 @@
 /*
  * RCWT (Raw Captions With Time) is a format native to ccextractor, a commonly
  * used open source tool for processing 608/708 Closed Captions (CC) sources.
- * It can be used to archive the original, raw CC bitstream and to produce
- * a source file for later CC processing or conversion. As a result,
- * it also allows for interopability with ccextractor for processing CC data
- * extracted via ffmpeg. The format is simple to parse and can be used
- * to retain all lines and variants of CC.
  *
  * This muxer implements the specification as of March 2024, which has
  * been stable and unchanged since April 2014.