chore: update README with vendor info

info reflects future repo location

README.md

-# Nexus
-This is a fork of the upstream Helm charts for installing Nexus Artifactor Repository Pro (i.e. Licenced Paid Version)     
+# Sonatype Nexus
 
-## Originally sourced from upstream, and minimially modified.
-Steps performed: 
-```
-kpt pkg get https://github.com/Oteemo/charts.git/charts/sonatype-nexus@sonatype-nexus-4.2.0 chart/
-```
+Source of truth for components, artifacts, binaries, etc.
 
-## Upstream Changes
+This chart was sourced from
+[Sonatype's Helm Charts.](https://github.com/sonatype/helm3-charts) with
+minimal changes.
 
-* TODO: no diff from upstream yet
+## Prerequisites
+
+- Kubernetes Cluster deployed
+- Kubernetes config installed in ~/.kube/config
+- Helm installed
 
 ## Iron Bank
 
-You can `pull` the registry1 images for:
-* Nexus [here](https://registry1.dso.mil/harbor/projects/3/repositories/sonatype%2Fnexus%2Fnexus) and view the container approval [here](https://ironbank.dso.mil/repomap/sonatype/nexus)
-* Nexus IQ Server [here](https://registry1.dso.mil/harbor/projects/3/repositories/sonatype%2Fnexus-iq-server%2Fnexus-iq-server) and view the container approval [here](https://ironbank.dso.mil/repomap/sonatype/nexus-iq-server)
+You can `pull` the Iron Bank image [here](https://registry1.dso.mil/harbor/projects/3/repositories/sonatype%2Fnexus%2Fnexus) and view the container approval [here](https://ironbank.dso.mil/repomap/sonatype/nexus).
+
+## Helm
+
+Please reference complete list of providable variables
+[here](https://github.com/sonatype/helm3-charts/tree/master/charts/nexus-repository-manager#configuration)
+
+```bash
+git clone https://repo1.dso.mil/platform-one/big-bang/apps/developer-tools/nexus-repository-manager.git
+helm install nexus-repository-manager chart
+```