info: add page (#3373)

pages/common/info.md

@@ -0,0 +1,16 @@
+# info
+
+> Reads documentation stored in the info format.
+> More information: <https://en.wikipedia.org/wiki/Info_(Unix)>.
+
+- Start reading top-level directory menu:
+
+`info`
+
+- Start reading at given menu item node from top-level directory:
+
+`info {{menu_item}}`
+
+- Start reading at second menu item within first menu item manual:
+
+`info {{first_menu_item}} {{second_menu_item}}`