docs: link directly to HA manifests (#11970)

This updates the manifest link directly to the High Availability header in the manifest readme. I chose this over linking to the `ha` folder since it explains the options and links to them.

Signed-off-by: Nicholas Morey <nicholas@morey.tech>
Co-authored-by: Michael Crenshaw <350466+crenshaw-dev@users.noreply.github.com>

docs/operator-manual/high_availability.md

@@ -4,7 +4,7 @@ Argo CD is largely stateless, all data is persisted as Kubernetes objects, which
 
 A set of HA manifests are provided for users who wish to run Argo CD in a highly available manner. This runs more containers, and runs Redis in HA mode.
 
-[Manifests ⧉](https://github.com/argoproj/argo-cd/tree/master/manifests) 
+[HA Manifests ⧉](https://github.com/argoproj/argo-cd/tree/master/manifests#high-availability) 
 
 > **NOTE:** The HA installation will require at least three different nodes due to pod anti-affinity roles in the
 > specs. Additionally, IPv6 only clusters are not supported.
@@ -188,4 +188,4 @@ spec:
     targetRevision: HEAD
     path: my-application
 # ...
-```
+```