Link to "Using the Linode Shell (LISH)" fixed

The link to "Using the Linode Shell (LISH)" did not work in [the docs page](https://www.linode.com/docs/networking/linux-static-ip-configuration), so I have changed it to an absolute URL rather than a relative URL.
Split the difference

This is a relative path that will work.
Merge pull request #1 from alexfornuto/patch-2

Split the difference
Merge pull request #63 from euantorano/patch-1

Link to "Using the Linode Shell (LISH)" fixed