dunstify: add page (#3501)

* dunstify: add page

* dunstify: add page

* fixed some formatting and wording issues, added notify-send --help command to get more info

pages/linux/dunstify.md

@@ -0,0 +1,20 @@
+# dunstify
+
+> A notification tool that is an extension of notify-send, but has more features based around dunst.
+> Works with all options that work for notify-send.
+
+- Show a notification with a given title and message:
+
+`dunstify {{"Title"}} {{"Message"}}`
+
+- Show a notification with specified urgency:
+
+`dunstify {{"Title"}} {{"Message}}" -u {{low|normal|critical}}`
+
+- Specify a message ID (overwrites any previous messages with the same ID):
+
+`dunstify {{"Title"}} {{"Message"}} -r {{123}}`
+
+- To see other possible options:
+
+`notify-send --help`