Replace replacement character

See https://github.com/confio/cosmjs-types/issues/92

packages/encoding/src/utf8.ts

@@ -15,8 +15,9 @@ export function toUtf8(str: string): Uint8Array {
 /**
  * Takes UTF-8 data and decodes it to a string.
  *
- * In lossy mode, the replacement character � is used to substitude invalid
- * encodings. By default lossy mode is off and invalid data will lead to exceptions.
+ * In lossy mode, the [REPLACEMENT CHARACTER](https://en.wikipedia.org/wiki/Specials_(Unicode_block))
+ * is used to substitude invalid encodings.
+ * By default lossy mode is off and invalid data will lead to exceptions.
  */
 export function fromUtf8(data: Uint8Array, lossy = false): string {
   const fatal = !lossy;