Rename Setup sidebar and page titles (#1246)

## Description

This saves us from having to add Corso everywhere and also addresses comments in a previous PR.

## Type of change

- [x] 🗺️ Documentation

docs/docs/intro.md

@@ -13,5 +13,5 @@ beyond M365, will expand based on the interest and needs of the community.
 ## Getting started
 
 You can follow the [Quick Start](/quickstart) guide for an end-to-end Corso walk through. Alternatively, follow
-the instructions in the [Initial Setup](/setup/concepts) section to dive into the details on how to configure and
+the instructions in the [Corso Setup](/setup/concepts) section to dive into the details on how to configure and
 run Corso.

docs/docs/setup/configuration.md

@@ -1,4 +1,4 @@
-# Configuring Corso
+# Configuration
 
 import Tabs from '@theme/Tabs';
 import TabItem from '@theme/TabItem';

docs/docs/setup/repos.md

@@ -2,7 +2,7 @@
 description: "Configure backup repository"
 ---
 
-# Corso repositories
+# Repositories
 
 A Corso [repository](concepts#corso-concepts) stores encrypted copies of your backup data. Repositories are
 supported on the following object storage systems:

docs/sidebars.js

@@ -19,7 +19,7 @@ const sidebars = {
     'quickstart',
     {
       type: 'category',
-      label: 'Initial setup',
+      label: 'Corso setup',
       items: ['setup/concepts', 'setup/m365_access', 'setup/repos', 'setup/configuration'],
     },
     {