Add Ubuntu integrations (#42)

Author: dandv

INTEGRATIONS.md

@@ -10,6 +10,19 @@ You can pull up the emoji keyboard by hitting <kbd>ctrl</kbd>+<kbd>⌘</kbd>+<kb
 
 You can pull up the emoji keyboard by hitting <kbd>Win</kbd>+<kbd>.</kbd>
 
+## Ubuntu 20
+
+You can press <kbd>Super</kbd> to search for the emoji name, but only the first 5 matches are displayed. This works for "book", but not for "bug".
+
+![Ubuntu Focal Fossa emoji search](https://user-images.githubusercontent.com/33569/82133882-d0ff1f00-97a5-11ea-9d8e-97fdf7dd41da.png)
+
+
+## Ubuntu (all versions)
+
+Launch the "Characters" application.
+
+![Characters](https://user-images.githubusercontent.com/33569/82133860-7bc30d80-97a5-11ea-9d91-33ad8caab611.png)
+
 ## Gnome Shell
 
 You can show a list of emoji to copy to your system clipboard using the [Emoji Selector](https://extensions.gnome.org/extension/1162/emoji-selector/) Gnome extension.