incus: add readme

modules/flake-parts/incus-image/README.md

@@ -0,0 +1,27 @@
+To build the image,
+
+```sh
+nix run .#incus-image-container-import public-container
+```
+
+To launch a container using it,
+
+```sh
+incus launch srid/public-container --ephemeral test
+```
+
+`public-container` runs nginx serving Hello world, which can test if the container is working.
+
+```sh
+# Find the IP
+❯ incus list
++------+---------+----------------------+-----------------------------------------------+-----------------------+-----------+
+| NAME |  STATE  |         IPV4         |                     IPV6                      |         TYPE          | SNAPSHOTS |
++------+---------+----------------------+-----------------------------------------------+-----------------------+-----------+
+| test | RUNNING | 10.162.27.156 (eth0) | fd42:ef6e:8271:3b9f:216:3eff:fea2:b8a6 (eth0) | CONTAINER (EPHEMERAL) | 0         |
++------+---------+----------------------+-----------------------------------------------+-----------------------+-----------+
+
+# curl container's nginx
+❯ curl 10.162.27.156
+Hello World%
+```