docs: update testnet version to 73

Bumps the usual version spec for the docs, so it's clear what version
should be downloaded. Given that 73 has a fresh chain, remove the
archive-url from the join instructions, because it's no longer correct.

Refs #4274

COMPATIBILITY.md

@@ -1,5 +1,4 @@
 | Application version (Name)| Penumbra crate version | CometBFT | Protobuf |
 | ------------------------- | ---------------------- | -------- | -------- |
 | 1 (Testnet 70)            | v0.70.x                | v0.37.5  |   v1     |
-| 2 (Testnet 71)            | v0.71.x                | v0.37.5  |   v1     |
-| 3 (Testnet 72)            | v0.72.x                | v0.37.5  |   v1     |
+| 2 (Testnet 73)            | v0.73.x                | v0.37.5  |   v1     |

docs/guide/src/node/pd/join-testnet.md

@@ -37,7 +37,6 @@ The following section describes how to join a testnet chain *which has never upg
 Once a chain upgrade occurs, a new-joining node must have access to an archive
 of historical, migrated state. When we upgrade the chain, we should update these
 docs to switch to the archive-url version:
--->
 
 ```shell
 pd testnet join --external-address IP_ADDRESS:26656 --moniker MY_NODE_NAME \
@@ -49,15 +48,16 @@ and `MY_NODE_NAME` is a moniker identifying your node. Other peers will try to c
 to your node over port `26656/TCP`. Finally, the `--archive-url` flag will fetch
 a tarball of historical blocks, so that your newly joining node can understand transactions
 that occurred prior to the most recent chain upgrade.
+-->
 
-<!--
 ```shell
 pd testnet join --external-address IP_ADDRESS:26656 --moniker MY_NODE_NAME
 ```
 
 where `IP_ADDRESS` (like `1.2.3.4`) is the public IP address of the node you're running,
 and `MY_NODE_NAME` is a moniker identifying your node. Other peers will try to connect
 to your node over port `26656/TCP`.
+<!--
 ### End join customization
 -->
 

docs/guide/src/penumbra_version.md

@@ -1 +1 @@
-v0.72.0
+v0.73.0