Add HA guide for self-hosted Enterprise (#812)

* render mermaid disgrams

* wip: add ha docs

* improve high availability guide

* fix review

* remove nav links and references

* remove dead server.authSecret references

* fix Redis troubleshooting command using non-existent env var

* correct startup-log order

src/components/Code.jsx

@@ -11,6 +11,7 @@ import clsx from 'clsx'
 import { create } from 'zustand'
 
 import { Tag } from '@/components/Tag'
+import { Mermaid } from '@/components/Mermaid'
 
 const languageNames = {
   js: 'JavaScript',
@@ -290,6 +291,10 @@ export function Code({ children, ...props }) {
 export function Pre({ children, ...props }) {
   let isGrouped = useContext(CodeGroupContext)
 
+  if (props.language === 'mermaid') {
+    return <Mermaid chart={props.code} />
+  }
+
   if (isGrouped) {
     return children
   }