Overhauled the Boot Rescue section (#616)

- Split the original file into multiple individual guides
- Re-write the guides using the new style guide

The purpose of this re-organization is:
- Make the guides easier to read and follow
- Make it easier to find the solution to a problem

Author: deoxys94

docs/user/troubleshooting/boot-rescue.md

@@ -0,0 +1,59 @@
+---
+title: I see an emergency shell or error message during startup
+summary: Troubleshooting the boot process for Solus
+---
+
+import BootAndChroot from "./snippets/_mount_partitions.mdx";
+import UnmountAll from "./snippets/_unmount_partitions.mdx";
+import WhatToDoNext from "./snippets/_contact_team.mdx";
+
+## Cause
+
+This issue might happen when the `/etc/fstab` file contains an entry for a storage device that isn't available during system startup, for example, disconnected USB drives or unavailable network file system (NFS) mounts.
+
+When trying to mount the device, the system fails and displays an emergency shell or error message.
+
+## Before your start
+
+For this procedure, you need:
+
+- [A Solus live USB](../../quick-start/installation/#creating-bootable-media)
+- Your disk encryption password, if your system is encrypted
+
+## Procedure
+
+1. Shut down your system.
+1. Boot from a Solus live USB.
+1.  Mount the partitions of your Solus system.
+
+    <details>
+      <BootAndChroot />
+    </details>
+
+1.  Prevent the system from trying to mount unavailable devices.
+
+    <details>
+    1. Edit `/etc/fstab` using `nano`:
+    	```bash
+    	nano /etc/fstab
+    	```
+    2. Find all the unavailable devices.
+    3. Add the `noauto` option to the line corresponding to the unavailable device.
+
+       For example:
+
+       ```bash
+       UUID=XXXXXX  /mnt/mydisk  exfat  noauto,uid=1000,gid=1000,umask=0022  0  0
+       ```
+    4. Save the file and restart your system.
+
+    </details>
+
+1.  Unmount all the Solus partitions.
+    <details>
+      <UnmountAll />
+    </details>
+
+## What to do next
+
+<WhatToDoNext />

docs/user/troubleshooting/boot-rescue/emergency-shell-startup.mdx

@@ -0,0 +1,23 @@
+---
+title: Boot Rescue
+summary: Troubleshooting the boot process for Solus
+---
+
+# Boot Rescue
+
+When your Solus system fails to start up, several common issues might be the cause:
+
+- On computers with multiple operating systems, another operating system controlling the startup sequence might not show Solus after a system update
+- System updates (particularly kernel updates) that didn't complete properly on either legacy BIOS or UEFI systems
+- Hardware changes such as adding or removing disks, or changes to disk identifiers (UUIDs) or mount points
+
+This guide helps you diagnose your specific startup issue and provides instructions to restore access to your Solus system.
+
+## Quick diagnosis
+
+Identify your issue by selecting the scenario that matches your situation:
+
+- [Solus does not appear in the startup menu](./solus-not-in-boot-menu.md)
+- [I see an emergency shell or error message during startup](./emergency-shell-startup.mdx)
+- [My system won't boot after an update](./system-not-working-after-update.mdx)
+- [I changed hardware and now my system won't boot](./system-not-working-hardware-change.mdx)

docs/user/troubleshooting/boot-rescue/index.md

@@ -0,0 +1,3 @@
+Restart your system and verify if the problem persists.
+
+If you are still unable to access your Solus system after following this guide, [contact us through any of the support channels](../../../user/intro/#support-channels).