Add Algolia docsearch to Corso docs (#1844)

## Description

This should be forever-free under Algolia's open source support.

## Does this PR need a docs update or release note?

- [x] ⛔ No 

## Type of change

- [x] 🌻 Feature
- [x] 🗺️ Documentation

## Test Plan

- [x] 💪 Manual

website/docusaurus.config.js

@@ -163,6 +163,13 @@ const config = {
         },
       },
 
+      algolia: {
+        appId: 'EPJZU1WKE7',
+        apiKey: 'd432a94741013719fdd0d78275c7aa9c',
+        indexName: 'corsobackup',
+        contextualSearch: true,
+      },
+
       image: 'img/cloudbackup.png',
 
       metadata : [

website/src/css/custom.scss

@@ -108,6 +108,7 @@ html[data-theme='dark'] {
   --ifm-background-color: #111629;
   --ifm-navbar-background-color: #111629;
   --ifm-link-color: #087EA4;
+  --docsearch-primary-color: #5468ff;
 }
 
 .footer {