Fix typo in public docs about manifest branch

The branch published on the website is actually v0.14 but `_index.md`
is using the same text as in the `main` branch misleading warning
against using the displayed manifests.

Signed-off-by: Benjamin Habié <adamency@protonmail.com>

website/content/installation/_index.md

@@ -75,7 +75,7 @@ If you want to deploy MetalLB using the [experimental FRR-K8s mode]({{% relref "
 kubectl apply -f https://raw.githubusercontent.com/metallb/metallb/v0.14.3/config/manifests/metallb-frr-k8s.yaml
 ```
 
-Please do note that these manifests deploy MetalLB from the main development branch. We highly encourage cloud operators to deploy a stable released version of MetalLB on production environments!
+These manifests deploy MetalLB from a release branch. Indeed, we highly encourage cloud operators to deploy a stable released version of MetalLB (instead of manifests from the main branch) on production environments!
 
 {{% /notice %}}