docs(changelog): describe the encoder entries by content

CHANGELOG.md

@@ -27,7 +27,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
   (`$(32-7)`, `$~63`, `(index*4)(base)`) fold at parse.  Expansion
   happens only on the assembly path: `gasm lint`, `gasm fmt` and the
   language server keep reading the raw file.
-- **The GOROOT instruction wave, part 1.**  The encoder now covers the
+- **Encoder coverage: the instruction families GOROOT's real code
+  uses.**  The encoder now covers the
   instruction families GOROOT's real code uses that gasm lacked,
   byte-verified against `go tool asm`: on amd64 the carry ALU, the
   atomics (CMPXCHG, XADD, XCHG), AES-NI, SHA-1/256, PCLMULQDQ, CRC32,
@@ -43,7 +44,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
   Also fixed on the way: arm64 `CASD`/`CASW` lacked an opcode bit, and
   riscv64 `VSETVLI` with an immediate length now canonicalises to
   `vsetivli` as the toolchain does.
-- **The GOROOT instruction wave, part 2.**  The encoder gains the
+- **Encoder coverage: quad-register AVX-512 and floating-point
+  immediates.**  The encoder gains the
   quad-register AVX-512 families (4FMAPS, 4FNMADD, 4VNNIW, VP4DPWSSD,
   VP4DPWSSDS) with the register list riding the inverted V'VVVV field,
   floating-point immediates on the SSE scalar moves and arithmetic