feat: add PawSQL docs examples and image CI

internal/postgres/provisioner_test.go

@@ -0,0 +1,19 @@
+package postgres
+
+import "testing"
+
+func TestPostgresDataMount(t *testing.T) {
+	tests := []struct {
+		image string
+		want  string
+	}{
+		{"postgres:16", "/var/lib/postgresql/data"},
+		{"postgres:17", "/var/lib/postgresql/data"},
+		{"postgres:18", "/var/lib/postgresql"},
+	}
+	for _, test := range tests {
+		if got := postgresDataMount(test.image); got != test.want {
+			t.Errorf("postgresDataMount(%q) = %q, want %q", test.image, got, test.want)
+		}
+	}
+}