Fix AsciiDoc missing attribute references

docs/modules/ROOT/pages/erc1155.adoc

@@ -94,9 +94,9 @@ The metadata uri can be obtained:
 "https://game.example/api/item/{id}.json"
 ----
 
-The `uri` can include the string `{id}` which clients must replace with the actual token ID, in lowercase hexadecimal (with no 0x prefix) and leading zero padded to 64 hex characters.
+The `uri` can include the string `++{id}++` which clients must replace with the actual token ID, in lowercase hexadecimal (with no 0x prefix) and leading zero padded to 64 hex characters.
 
-For token ID `2` and uri `https://game.example/api/item/{id}.json` clients would replace `{id}` with `0000000000000000000000000000000000000000000000000000000000000002` to retrieve JSON at `https://game.example/api/item/0000000000000000000000000000000000000000000000000000000000000002.json`.
+For token ID `2` and uri `++https://game.example/api/item/{id}.json++` clients would replace `++{id}++` with `0000000000000000000000000000000000000000000000000000000000000002` to retrieve JSON at `https://game.example/api/item/0000000000000000000000000000000000000000000000000000000000000002.json`.
 
 The JSON document for token ID 2 might look something like: