link: add page (#2274)

pages/linux/link.md

@@ -0,0 +1,8 @@
+# link
+
+> Create a hard link to an existing file.
+> For more options, see the `ln` command.
+
+- Create a hard link from a new file to an existing file:
+
+`link {{path/to/existing_file}} {{path/to/new_file}}`