Attempting to reduce docs to single platform (#1258)

##

We are going to make the following changes to the Object Store docs as
part of a larger QC/Content pass:

### Left Navigation

We want to modify the left navigation flow to be a natural progression
from a basic setup to more advanced.

For example:

- Core Concepts
  - Deployment Architecture
  - Availability and Resiliency
  - Erasure Coding and Object Healing
  - Object Scanner
  - Site Replication and Failover
  - Thresholds and Limits
- Installation
  - Deployment Checklist
  - Deploy MinIO on Kubernetes
  - Deploy MinIO on Red Hat Linux
  - Deploy MinIO on Ubuntu Linux
  - Deploy MinIO for Development (MacOS, Windows, Container)
- Security and Encryption (Conceptual Overview)
  - Network Encryption (TLS) (Conceptual overview)
    - Enable Network Encryption using Single Domain
    - Enable Network Encryption using Multiple Domains
    - Enable Network Encryption using certmanager (Kubernetes only)
  - Data Encryption (SSE) (Conceptual overview)
    - Enable SSE using AIStor Key Management Server
    - Enable SSE using KES (Summary page + linkouts)
  - External Identity Management (Conceptual Overview)
    - Enable External Identity management using OpenID
    - Enable External Identity management using AD/LDAP
- Backup and Recovery
  - Create a Multi-Site Replication Configuration
  - Recovery after Hardware Failure
    - Recover after drive failure
    - Recover after node failure
    - Recover after site failure
- Monitoring and Alerts
  - Metrics and Alerting (v3 reference)
    - Monitoring and Alerting using Prometheus
    - Monitoring and Alerting using InfluxDB
    - Monitoring and Alerting using Grafana
    - Metrics V2 Reference
  - Publish Server and Audit Logs to External Services
  - MinIO Healthcheck API

The Administration, Developer, and Reference sections will remain as-is
for now.

http://192.241.195.202:9000/staging/singleplat/mindocs/index.html

# Goals

Maintaining multiple platforms is getting to be too much, and based on
analytics the actual number of users taking advantage of it is minimal.

Furthermore, the majority of traffic is to installation pages.

Therefore we're going to try to collapse back into a single MinIO Object
Storage product, and use simple navigation and on-page selectors to
handle Baremetal vs Kubernetes.

This may also help to eventually stage us to migrate to Hugo + Markdown

---------

Co-authored-by: Daryl White <53910321+djwfyi@users.noreply.github.com>
Co-authored-by: Rushan <rushenn@minio.io>
Co-authored-by: rushenn <rushenn123@gmail.com>

source/_static/js/main.js

@@ -318,7 +318,7 @@ window.addEventListener("DOMContentLoaded", (event) => {
       else if (page_title === "Software Development Kits (SDK)") {
         list[i].insertAdjacentElement('beforebegin',developerPersona);
       }
-      else if (page_title === "MinIO Client") {
+      else if (page_title === "Kubernetes Reference") {
         list[i].insertAdjacentElement('beforebegin',referencePersona);
       }
     }