ARC-20 - Update reference implementation

ARCs/arc-0020.md

@@ -32,7 +32,7 @@
 issued, it can't be re-configured (its unit name, decimals, maximum supply).
 Also, it is freely transferable (unless frozen). This prevents developers from
 specifying additional business logic to be checked while transferring it (think
-of royalties or vesting https://en.wikipedia.org/wiki/Vesting).
+of royalties or <a href="https://en.wikipedia.org/wiki/Vesting">vesting</a>).
 
 Enforcing transfer conditions requires freezing the asset and transferring it
 through a clawback operation — which results in a process that is opaque to
@@ -58,8 +58,8 @@
 
 ### ABI Interface
 
-The ABI interface specified here draws inspiration from the transaction
-reference https://developer.algorand.org/docs/get-details/asa/#asset-functions
+The ABI interface specified here draws inspiration from the <a href="https://dev.algorand.co/concepts/assets/overview/#asset-parameters">
+parameters</a> and <a href="https://dev.algorand.co/concepts/transactions/reference/">transaction reference</a>
 of an Algorand Standard Asset (ASA).
 
 To provide a unified and familiar interface between the Algorand Standard Asset
@@ -614,11 +614,11 @@
 A Smart ASA MUST specify the ID of its controlling Smart Contract.
 
 If the Smart ASA also conforms to any ARC that supports additional `properties`
-([ARC-3](./arc-0003.md), [ARC-69](./arc-0069.md)), then it MUST include a
+([ARC-3](./arc-0003.md), [ARC-89](./arc-0089.md)), then it MUST include a
 `arc-20` key and set the corresponding value to a map, including the ID of the
 controlling Smart Contract as a value for the key `application-id`. For example:
 
-```javascript
+```json
 {
   //...
   "properties": {
@@ -631,6 +631,9 @@
 }
 ```
 
+It is RECOMMENDED to use the [ARC-89](./arc-0089.md) ASA Metadata Registry to declare
+support for this ARC and to discover the controlling Smart Contract of a Smart ASA.
+
 > To avoid ecosystem fragmentation this ARC does NOT propose any new method to
 > specify the metadata of an ASA. Instead, it only extends already
 > existing standards.
@@ -692,7 +695,8 @@
 - Re-configuring the ASA, by setting its `ClawbackAddr` to the account of the
   controlling Smart Contract.
 - Associating the ID of the Smart Contract to the ASA (see
-  [metadata](#metadata)).
+[metadata](#metadata)) with an [ARC-2](./arc-0002.md) message, following the ASA
+Metadata Registry [backward compatibility guidelines](./arc-0089.md#backwards-compatibility).
 
 ### [ARC-18](./arc-0018.md)
 
@@ -703,7 +707,8 @@
 
 ## Reference Implementation
 
-A reference implementation is available [here](../assets/arc-0020)
+A <a href="https://github.com/algorandfoundation/arc20">reference implementation<\a>
+is maintained by the Algorand Foundation.
 
 ## Security Considerations