readme: add instructions on running pcmt [skip ci]

README.md

@@ -22,5 +22,24 @@
 </p>
 
 
+### How to try this out
+
+with [`podman`](https://podman.io/) and [`just`](https://github.com/casey/just)
+installed, run the following:
+```sh
+# build the image locally using kaniko.
+just kaniko
+
+# start postgres.
+just dbstart
+
+# make sure to supply real CONNSTRING values for production environment.
+podman run --rm -it -e PCMT_DBTYPE=postgres \
+    -e PCMT_CONNSTRING="host=127.0.0.1 port=5432 sslmode=disable dbname=postgres password=postgres"
+    -e PCMT_LIVE=False docker.io/immawanderer/pcmt:testbuild \
+    -config /etc/pcmt/config.dhall
+```
+
+
 ### LICENSE
 AGPL-3.0-only (see [LICENSE](LICENSE) for details).