Use correct list syntax in containers-registries.conf(5)

Four leading spaces are interpreted by go-md2man as a code block.

Add a new line to start a new paraagraph, so that go-md2man recognizes
the list syntax.

Signed-off-by: Miloslav Trmač <mitr@redhat.com>

docs/containers-registries.conf.5.md

@@ -238,9 +238,10 @@ location = "example-mirror-1.local/mirrors/foo"
 insecure = true
 ```
 Given the above, a pull of `example.com/foo/image:latest` will try:
-    1. `example-mirror-0.local/mirror-for-foo/image:latest`
-    2. `example-mirror-1.local/mirrors/foo/image:latest`
-    3. `internal-registry-for-example.net/bar/image:latest`
+
+1. `example-mirror-0.local/mirror-for-foo/image:latest`
+2. `example-mirror-1.local/mirrors/foo/image:latest`
+3. `internal-registry-for-example.net/bar/image:latest`
 
 in order, and use the first one that exists.