Adding a sentence to the index to point people towards the "activate … (#32730)

* Adding a sentence to the index to point people towards the "activate license" page if they want to complete installation of their Grafana Enterprise installation. Also made a minor change to the two sentences before to make them more consistent.

* Made Ursula's copy changes.

* Apply suggestions from code review

Fixed relref and made copy change suggested by Jita.

Co-authored-by: achatterjee-grafana <70489351+achatterjee-grafana@users.noreply.github.com>

Co-authored-by: achatterjee-grafana <70489351+achatterjee-grafana@users.noreply.github.com>
Co-authored-by: Piotr Jamróz <pm.jamroz@gmail.com>

docs/sources/installation/_index.md

@@ -18,5 +18,7 @@ This section discusses the hardware and software requirements as well as the pro
 - [Run Docker image]({{< relref "docker" >}})
 - [Deploy Grafana on Kubernetes]({{< relref "kubernetes" >}})
 
-Refer to [Upgrade Grafana]({{< relref "upgrading.md" >}}) topic. If you need to restart Grafana, refer to the [Restart Grafana]({{< relref "Restart-grafana.md" >}})
-topic for detailed information.
+For upgrade instructions, refer to [Upgrade Grafana]({{< relref "upgrading.md" >}}).
+To restart Grafana, refer to [Restart Grafana]({{< relref "restart-grafana.md" >}}).
+
+To install Grafana Enterprise, refer to the instructions for installing Grafana on your system. Then, refer to [Activate an Enterprise license]({{< relref "../enterprise/activate-license.md" >}}).