Add note about Noto Color Emoji font support by default

In modern Linux distros.

Source: https://www.omgubuntu.co.uk/2018/06/use-emoji-linux-ubuntu-apps

doc/user/markdown.md

@@ -234,7 +234,12 @@ https://gitlab.com/gitlab-org/gitlab-ce/blob/master/doc/user/markdown.md#emoji
 	Consult the [Emoji Cheat Sheet](https://www.emojicopy.com) for a list of all supported emoji codes. :thumbsup:
-	Most emoji are natively supported on macOS, Windows, iOS, Android and will fallback to image-based emoji where there is lack of support. On Linux, you can download [Noto Color Emoji](https://www.google.com/get/noto/help/emoji/) to get full native emoji support.
+	Most emoji are natively supported on macOS, Windows, iOS, Android and will fallback to image-based emoji where there is lack of support.
+
+	On Linux, you can download [Noto Color Emoji](https://www.google.com/get/noto/help/emoji/) to get full native emoji support.
+
+	Ubuntu 18.04 (like many modern Linux distros) has this font installed by default.
+
 Sometimes you want to :monkey: around a bit and add some :star2: to your :speech_balloon:. Well we have a gift for you:
@@ -246,7 +251,13 @@ If you are new to this, don't be :fearful:. You can easily join the emoji :famil
 Consult the [Emoji Cheat Sheet](https://www.emojicopy.com) for a list of all supported emoji codes. :thumbsup:
-Most emoji are natively supported on macOS, Windows, iOS, Android and will fallback to image-based emoji where there is lack of support. On Linux, you can download [Noto Color Emoji](https://www.google.com/get/noto/help/emoji/) to get full native emoji support.
+Most emoji are natively supported on macOS, Windows, iOS, Android and will fallback to image-based emoji where there is lack of support.
+
+On Linux, you can download [Noto Color Emoji](https://www.google.com/get/noto/help/emoji/) to get full native emoji support.
+
+Ubuntu 18.04 (like many modern Linux distros) has this font installed by default.
+
+
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