dialog: add page (#15630)

Co-authored-by: K.B.Dharun Krishna <kbdharunkrishna@gmail.com>

pages/linux/dialog.md

@@ -0,0 +1,16 @@
+# dialog
+
+> Display dialog boxes on the terminal.
+> More information: <https://manned.org/dialog>.
+
+- Display a message:
+
+`dialog --msgbox "{{Message}}" {{height}} {{width}}`
+
+- Prompt the user for text:
+
+`dialog --inputbox "{{Enter text:}}" {{8}} {{40}} 2>{{output.txt}}`
+
+- Prompt the user for a yes/no question:
+
+`dialog --yesno "{{Continue?}}" {{7}} {{40}}`