Adds some examples for ln

Hopefully this will help people remember if the source
is the first or second argument

common/ln.md

@@ -0,0 +1,11 @@
+# ln
+
+> Creates links to files and folders
+
+- create a symbolic link to a file or folder
+
+`ln -s {{path/to/original/file}} {{path/to/link}}`
+
+- create a hard link to a file or folder
+
+`ln {{path/to/original/file}} {{path/to/link}}`