add v21 upgrade

juno-1/2800_v21_UPGRADE.md

@@ -0,0 +1,27 @@
+# Juno v21 - Upgrade
+
+Additional links:
+
+- [Proposal #340](https://www.mintscan.io/juno/proposals/340).
+- [The v21.0.0 changelog is viewable here](https://github.com/CosmosContracts/juno/releases/tag/v21.0.0).
+
+The target block for this upgrade is [14556500](https://www.mintscan.io/juno/blocks/14556500), which is expected to arrive on _Mon March 11th, 2023 at 1430UTC_, +/- 1 hour.
+
+These are the instructions you will need if you run cosmo-visor:
+
+```bash
+cd juno
+git fetch --tags && git checkout v21.0.0
+make build && make install
+
+junod version --long | grep "cosmos_sdk_version\|commit\|version:"
+# commit: e98863bf7112f4b117a2114e22f7482367362764
+# cosmos_sdk_version: v0.47.6
+# version: v21.0.0
+
+mkdir -p $DAEMON_HOME/cosmovisor/upgrades/v21/bin && cp $HOME/go/bin/junod $DAEMON_HOME/cosmovisor/upgrades/v21/bin
+
+$DAEMON_HOME/cosmovisor/upgrades/v21/bin/junod version
+```
+
+Alternatively, you can run the upgrade the old-fashioned way.