Update tomb steganography link

moved to their own site 

dyne/tomb@0c8d4cf

and is in "Advanced usage" section.

Signed-off-by: jermanuts <109705802+jermanuts@users.noreply.github.com>

docs/encryption.md

@@ -259,7 +259,7 @@ Tools with command-line interfaces are useful for integrating [shell scripts](ht
 
 ![Tomb logo](assets/img/encryption-software/tomb.png){ align=right }
 
-**Tomb** is a command-line shell wrapper for LUKS. It supports steganography via [third-party tools](https://github.com/dyne/Tomb#how-does-it-work).
+**Tomb** is a command-line shell wrapper for LUKS. It supports steganography via [third-party tools](https://dyne.org/software/tomb/#advanced-usage).
 
 [:octicons-home-16: Homepage](https://dyne.org/software/tomb){ .md-button .md-button--primary }
 [:octicons-info-16:](https://github.com/dyne/Tomb/wiki){ .card-link title=Documentation}