Remove reference-decoder citations from a public MIT-licensed repo

This crate is MIT licensed. Comments citing another decoder's internal symbols
and reproducing its tables verbatim create licence risk that no engineering
benefit justifies, so every such citation is replaced with the primary source:
ETSI TS 102 114 §5.3.1.

Eleven sites across src/mux/codec/dts.rs and src/mux/mp4/audio.rs. The technical
substance is unchanged in every case — the deficit-sample-count semantics, the
reserved-field skips, the invalid LFF value, and the 16 legal AMODE codes are all
spec facts and are now attributed as such. Four CHANGELOG entries that named a
validator are reworded; the "no a reference decoder" dependency claim stays, since stating
what this project does NOT depend on carries no risk.

I initially argued this was a false positive on the grounds that the project's
hygiene rules name internal infrastructure and reverse-engineering material, not
open-source citations, and that a channel-count table from a standard is fact
rather than expression. That reasoning missed the point: the exposure is MIT
distributing text derived from GPL/LGPL sources, and that is the maintainer's
risk to weigh, not mine. Reversed in full.

src/mux/mp4/audio.rs

@@ -240,7 +240,7 @@ const DTS_SFREQ: [u32; 16] = [
     24_000, 48_000, 96_000, 192_000,
 ];
 /// DTS core base channel count per `AMODE` (all 16 defined values). Matches the
-/// reference `ff_dca_channels[16]` table (ETSI TS 102 114) that the decodability
+/// per-AMODE channel counts in ETSI TS 102 114 §5.3.1, the same table the decodability
 /// gate in `dts.rs` (`DTS_AMODE_COUNT`) also uses, so a spec-legal DTS-ES / 6.1 /
 /// 7.1 core (AMODE 13→7, 14/15→8) is DECLARED with its true channel count in the
 /// mp4 AudioSampleEntry / `ddts` box rather than a truncated 6.
@@ -613,7 +613,7 @@ mod tests {
     fn dts_high_amode_channel_counts_are_declared() {
         // The 16-entry DTS_AMODE_CH must declare the true core channel count for the
         // spec-legal high AMODEs that now pass the decodability gate: AMODE 13→7,
-        // 14→8, 15→8 (ETSI TS 102 114 / ff_dca_channels). The old 10-entry table
+        // 14→8, 15→8 (ETSI TS 102 114 §5.3.1). The old 10-entry table
         // fell through `unwrap_or(6)` → every one of these was declared as 6.
         //
         // Frame layout (mirrors dts_core_5_1_and_ddts): SFREQ=13 (48k), LFF=0 (no