docs: remove core install commands from getting started (argoproj#16735)

* docs: remove core install commands from getting started

I often accidentally run the core install commands when quickly copying and pasting commands from the getting started guide, which leads to confusion. I've also spent plenty of time helping newcomers to Argo CD who have done the same and are confused when they can't reach the UI.

Given that this is a "getting started" guide, it's ideal to provide only the commands required. I've removed the commands and left the link out to the core install page for those who are interested in going down that path.

Signed-off-by: Nicholas Morey <nicholas@morey.tech>

* fix: use link to install commands in core docs

Signed-off-by: Nicholas Morey <nicholas@morey.tech>

* fix: use tip and improve wording

Signed-off-by: Nicholas Morey <nicholas@morey.tech>

---------

Signed-off-by: Nicholas Morey <nicholas@morey.tech>

docs/getting_started.md

@@ -22,12 +22,8 @@ This will create a new namespace, `argocd`, where Argo CD services and applicati
     The installation manifests include `ClusterRoleBinding` resources that reference `argocd` namespace. If you are installing Argo CD into a different
     namespace then make sure to update the namespace reference.
 
-If you are not interested in UI, SSO, multi-cluster features then you can install [core](operator-manual/installation.md#core) Argo CD components only:
-
-```bash
-kubectl create namespace argocd
-kubectl apply -n argocd -f https://raw.githubusercontent.com/argoproj/argo-cd/stable/manifests/core-install.yaml
-```
+!!! tip
+    If you are not interested in UI, SSO, and multi-cluster features, then you can install only the [core](operator-manual/core/#installing) Argo CD components.
 
 This default installation will have a self-signed certificate and cannot be accessed without a bit of extra work.
 Do one of: