Fix markdown indentation level

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

docs/reference/commandline/images.md

@@ -267,22 +267,23 @@ The `reference` filter shows only images whose reference matches
 the specified pattern.
 
 ```bash
-    $ docker images
+$ docker images
 
-    REPOSITORY          TAG                 IMAGE ID            CREATED             SIZE
-    busybox             latest              e02e811dd08f        5 weeks ago         1.09 MB
-    busybox             uclibc              e02e811dd08f        5 weeks ago         1.09 MB
-    busybox             musl                733eb3059dce        5 weeks ago         1.21 MB
-    busybox             glibc               21c16b6787c6        5 weeks ago         4.19 MB
+REPOSITORY          TAG                 IMAGE ID            CREATED             SIZE
+busybox             latest              e02e811dd08f        5 weeks ago         1.09 MB
+busybox             uclibc              e02e811dd08f        5 weeks ago         1.09 MB
+busybox             musl                733eb3059dce        5 weeks ago         1.21 MB
+busybox             glibc               21c16b6787c6        5 weeks ago         4.19 MB
 ```
 
 Filtering with `reference` would give:
 
 ```bash
-    $ docker images --filter=reference='busy*:*libc'
-    REPOSITORY          TAG                 IMAGE ID            CREATED             SIZE
-    busybox             uclibc              e02e811dd08f        5 weeks ago         1.09 MB
-    busybox             glibc               21c16b6787c6        5 weeks ago         4.19 MB
+$ docker images --filter=reference='busy*:*libc'
+
+REPOSITORY          TAG                 IMAGE ID            CREATED             SIZE
+busybox             uclibc              e02e811dd08f        5 weeks ago         1.09 MB
+busybox             glibc               21c16b6787c6        5 weeks ago         4.19 MB
 ```
 
 ### Format the output