Update use-fleet-behind-a-proxy.md

[emilianolangella]

I can't find "Agent Environment Vars" under the "Advanced Options", but only under "Cluster Configuration":

[martyav]

@emilianolangella what version are you running?

I checked an instance running v2.7 and Agent Environment Variables is located as described in the current docs.

If you're on v2.8, then when we update the versioned pages we only need to update v2.8 and not any further back.

[emilianolangella]

I have 2.8.3.

[btat]

The layout difference depends on if RKE or RKE2/K3s is used. We generally use Tabs to differentiate that.

[btat]

I can't make a direct suggestion due to the deleted line, but it should look something like this:

<Tabs groupId="k8s-distro">
<TabItem value="RKE2/K3s" default>
1. Click **☰ > Cluster Management**.
1. Go to the cluster where you want to add environment variables and click **⋮ > Edit Config**.
1. Click **Agent Environment Vars** under **Cluster configuration**.
1. Click **Add**.
1. Enter the [required environment variables](#required-environment-variables)
1. Click **Save**.
</TabItem>
<TabItem value="RKE" default>
1. Click **☰ > Cluster Management**.
1. Go to the cluster where you want to add environment variables and click **⋮ > Edit Config**.
1. Click **Advanced Options**.
1. Click **Add Environment Variable**.
1. Enter the [required environment variables](#required-environment-variables)
1. Click **Save**.
</TabItem>
</Tabs>