Match single-byte.d.ts header to README.md documentation

Co-authored-by: ChALkeR <291301+ChALkeR@users.noreply.github.com>

Author: Copilot

single-byte.d.ts

@@ -1,13 +1,32 @@
 /**
- * Single-byte encoding/decoding
- *
  * ```js
  * import { createSinglebyteDecoder, createSinglebyteEncoder } from '@exodus/bytes/single-byte.js'
- * import { latin1toString, latin1fromString } from '@exodus/bytes/single-byte.js'
  * import { windows1252toString, windows1252fromString } from '@exodus/bytes/single-byte.js'
+ * import { latin1toString, latin1fromString } from '@exodus/bytes/single-byte.js'
  * ```
  *
- * Supports various single-byte character encodings like ISO-8859-* and Windows-125*.
+ * Decode / encode the legacy single-byte encodings according to the
+ * [Encoding standard](https://encoding.spec.whatwg.org/)
+ * ([§9](https://encoding.spec.whatwg.org/#legacy-single-byte-encodings),
+ * [§14.5](https://encoding.spec.whatwg.org/#x-user-defined)),
+ * and [unicode.org](https://unicode.org/Public/MAPPINGS/ISO8859) `iso-8859-*` mappings.
+ *
+ * Supports all single-byte encodings listed in the WHATWG Encoding standard:
+ * `ibm866`, `iso-8859-2`, `iso-8859-3`, `iso-8859-4`, `iso-8859-5`, `iso-8859-6`, `iso-8859-7`, `iso-8859-8`,
+ * `iso-8859-8-i`, `iso-8859-10`, `iso-8859-13`, `iso-8859-14`, `iso-8859-15`, `iso-8859-16`, `koi8-r`, `koi8-u`,
+ * `macintosh`, `windows-874`, `windows-1250`, `windows-1251`, `windows-1252`, `windows-1253`, `windows-1254`,
+ * `windows-1255`, `windows-1256`, `windows-1257`, `windows-1258`, `x-mac-cyrillic` and `x-user-defined`.
+ *
+ * Also supports `iso-8859-1`, `iso-8859-9`, `iso-8859-11` as defined at
+ * [unicode.org](https://unicode.org/Public/MAPPINGS/ISO8859)
+ * (and all other `iso-8859-*` encodings there as they match WHATWG).
+ *
+ * > [!NOTE]
+ * > While all `iso-8859-*` encodings supported by the [WHATWG Encoding standard](https://encoding.spec.whatwg.org/) match
+ * > [unicode.org](https://unicode.org/Public/MAPPINGS/ISO8859), the WHATWG Encoding spec doesn't support
+ * > `iso-8859-1`, `iso-8859-9`, `iso-8859-11`, and instead maps them as labels to `windows-1252`, `windows-1254`, `windows-874`.\
+ * > `createSinglebyteDecoder()` (unlike `TextDecoder` or `legacyHookDecode()`) does not do such mapping,
+ * > so its results will differ from `TextDecoder` for those encoding names.
  *
  * @module @exodus/bytes/single-byte.js
  */