docs(asm): describe the four target architectures

Assisted-by: GLM 5.3 Flash

docs/asm/README.md

@@ -41,13 +41,16 @@ layers 1 or 2; it extends them.
 | [DIRECTIVES.md](DIRECTIVES.md) | 1 | TEXT, DATA, GLOBL, FUNCDATA, PCDATA, PCALIGN and the function flags |
 | [PREPROCESSOR.md](PREPROCESSOR.md) | 1 | `#include`, `#define`, `#ifdef` and friends, `-D`, `-I` |
 | [RUNTIME.md](RUNTIME.md) | 2 | ABI0, prototypes, `go_asm.h`, `funcdata.h`, `go vet` |
-| AMD64, ARM64, RISCV64, LOONG64 | 1, 3 | per architecture: registers, conventions, addressing, instruction families and the generated instruction appendices |
+| [AMD64.md](AMD64.md) | 1 | registers, addressing, the frame and split check, families, relocations |
+| [ARM64.md](ARM64.md) | 1 | registers, the MOV load and store series, special operand orders, SIMD |
+| [RISCV64.md](RISCV64.md) | 1 | registers and their constrained names, per class operand order, profiles, vector extension |
+| [LOONG64.md](LOONG64.md) | 1 | registers, width suffixes, vector element syntax, atomics and barriers |
+| INSTRUCTIONS-AMD64.md and the other three | 1 | generated per architecture inventory of every accepted mnemonic |
 | STANDALONE.md | 3 | the language outside Go |
 
 ## Status
 
-The common-language core and the Go-embedded layer are written and verified.
-The four per-architecture pages and their generated instruction appendices
-follow, architecture by architecture; STANDALONE.md lands with the standalone
-compilation phase. The object format these pages feed is specified in
-[GOOBJ.md](../GOOBJ.md).
+The common-language core, the Go-embedded layer, all four per-architecture
+pages and the generated instruction appendices are written and verified.
+STANDALONE.md lands with the standalone compilation phase. The object format
+these pages feed is specified in [GOOBJ.md](../GOOBJ.md).