chore: update README to give usage

Signed-off-by: Chris Gianelloni <[email protected]>

Author: wolf31o2

README.md

@@ -1,2 +1,20 @@
 # docker-cardano-db-sync
-Builds a cardano-db-sync on debian
+Builds a Cardano DB sync container from source on Debian. This image attempts
+to keep interface compatibility with `inputoutput/cardano-db-sync`, but may
+diverge slightly, particularly with any Nix-specific paths.
+
+## Running
+To run a Cardano DB sync on mainnet, attached to a local Cardano full node
+container running:
+```bash
+docker run --detach \
+  --name cardano-db-sync \
+  -v dbsync-state:/var/lib/cexplorer \
+  -v node-ipc:/node-ipc \
+  ghcr.io/cloudstruct/cardano-db-sync
+```
+
+DB sync logs can be followed:
+```bash
+docker logs -f cardano-db-sync
+```