Merge pull request #42 from cloudstruct/chore/docs-preview-usage

chore: document preview usage in readme

Author: wolf31o2

README.md

@@ -1,10 +1,13 @@
 # docker-cardano-node
+
 Builds a Cardano full node from source on Debian. This image attempts to keep
 interface compatibility with `inputoutput/cardano-node`, but may diverge
 slightly, particularly with any Nix-specific paths.
 
 ## Running a node
+
 To run a Cardano full node on mainnet:
+
 ```bash
 docker run --detach \
   --name cardano-node \
@@ -13,27 +16,56 @@ docker run --detach \
   -p 3001:3001 \
   ghcr.io/cloudstruct/cardano-node run
 ```
+
 The above maps port 3001 on the host to 3001 on the container, suitable
 for use as a mainnet relay node.
 
 Node logs can be followed:
+
 ```bash
 docker logs -f cardano-node
 ```
+
+Running a node on a different network uses a slightly different syntax.
+
+To run a Cardano full node on preview:
+
+```bash
+docker run --detach \
+  --name cardano-node \
+  -v node-data:/data/db \
+  -v node-ipc:/ipc \
+  -e NETWORK=preview \
+  -p 3001:3001 \
+  ghcr.io/cloudstruct/cardano-node
+```
+
 ## Running the CLI
+
 To run a Cardano CLI command, we use the `node-ipc` volume from our node.
+
 ```bash
 docker run --rm -ti \
   -v node-ipc:/opt/cardano/ipc \
   ghcr.io/cloudstruct/cardano-node cli <command>
 ```
+
 This can be added to a shell alias:
+
 ```bash
 alias cardano-cli="docker run --rm -ti \
   -v node-ipc:/opt/cardano/ipc \
   ghcr.io/cloudstruct/cardano-node cli"
 ```
+
 Now, you can use cardano-cli commands as you would, normally.
+
 ```bash
 cardano-cli query tip --mainnet
 ```
+
+Or, for preview:
+
+```bash
+cardano-cli query tip --network-magic 2
+```