Update and reorganize documentation

- Convert "Common Tasks" to "How-to Guides"
  (QubesOS/qubes-issues#6694)
- Make title capitalization consistent across docs
- Fix leftover h1 headings
- Reorganize various pages and topics
- Update permalinks to better match titles
- Create redirects for changed permalinks
- Miscellaneous cleanup

QubesOS/qubes-issues#6701

user/how-to-guides/how-to-use-optical-discs.md

@@ -0,0 +1,25 @@
+---
+lang: en
+layout: doc
+permalink: /doc/how-to-use-optical-discs/
+redirect_from:
+- /doc/optical-discs/
+- /doc/recording-optical-discs/
+- /en/doc/recording-optical-discs/
+ref: 204
+title: How to Use Optical Discs
+---
+
+
+Passthrough reading and recording (a.k.a., "burning") are not supported by Xen.
+Currently, the only options for reading and recording optical discs (e.g., CDs, DVDs, BRDs) in Qubes are:
+
+ 1. Use a USB optical drive.
+ 2. Attach a SATA optical drive to a secondary SATA controller, then assign this secondary SATA controller to a VM.
+ 3. Use a SATA optical drive attached to dom0.
+    (**Caution:** This option is [potentially dangerous](https://github.com/Qubes-Community/Contents/blob/master/docs/security/security-guidelines.md#dom0-precautions).)
+
+To access an optical disc via USB follow the [typical procedure for attaching a USB device](/doc/usb-devices/#with-the-command-line-tool), then check with the **Qubes Devices** widget to see what device in the target qube the USB optical drive was attached to.
+Typically this would be `sr0`.
+For example, if `sys-usb` has device `3-2` attached to the `work` qube's `sr0`, you would mount it with `mount /dev/sr0 /mnt/removable`.
+You could also write to a disc with `wodim -v dev=/dev/sr0 -eject /home/user/Qubes.iso`.