tests/integration: Describe pid test

Signed-off-by: Monika Kairaityte <[email protected]>

tests/integration/pid/README.txt

@@ -0,0 +1,13 @@
+This is the output of command "up -d" with corresponding "pid/docker-compose.yml" file:
+WARN[0000] freezer not supported: openat2 /sys/fs/cgroup/machine.slice/libpod-SHA.scope/cgroup.freeze: no such file or directory
+WARN[0000] lstat /sys/fs/cgroup/machine.slice/libpod-SHA.scope: no such file or directory
+pid_serv_1
+
+Command output corresponds to a closed (but not fixed) issue in "containers/podman":
+https://github.com/containers/podman/issues/11784
+
+The command was tested on:
+podman-compose version 1.3.0
+podman version 4.3.1
+
+Operating System: Debian GNU/Linux 12 (bookworm)