Redundant installation of `aka` plugin in quickstart

[calebschoepp]

This section seems redundant in the quickstart b/c AFAICT the previous install script used already installs the aka plugin.

## Install the `aka` Plugin for Spin

In order to interact with Fermyon Wasm Functions (Login, Deploy, etc), you need to install the Fermyon Wasm Functions for Akamai Spin plugin (`aka`). The plugin can be installed using this command:

<!-- @selectiveCpy -->

``
$ spin plugin install aka
``