Replace rendered example with image

Because the markdown wouldn't have been rendered
on docs.gitlab.com

doc/user/markdown.md

@@ -246,7 +246,7 @@ https://gitlab.com/gitlab-org/gitlab-ce/blob/master/doc/user/markdown.md#inline-
 
 With inline diffs tags you can display {+ additions +} or [- deletions -].
 
-The wrapping tags can be either curly braces or square brackets: [+ additions +] or {- deletions -}.
+The wrapping tags can be either curly braces or square brackets.
 
 Examples:
 
@@ -257,6 +257,10 @@ Examples:
 - [- deletions -]
 ```
 
+becomes:
+
+![inline diffs tags rendered](img/markdown_inline_diffs_tags_rendered.png)
+
 However the wrapping tags cannot be mixed as such:
 
 ```