Since Version 13, the documentation for Wolfram desktop products is installed separately from the main product.

The documentation installers for Windows, macOS and Linux are available in your Wolfram User Portal on the My Products and Services tab.

Direct File Download

1. Quit any previous installations of Wolfram products that are running on your machine.
2. Go to your Wolfram product’s download page in the Wolfram User Portal.
   
3. Click the Linux link in the “Documentation Only” line for your language and “Direct File Download” column.
4. After download is completed, open a terminal and change the directory to where the installer is located.
5. Installing a Wolfram product’s documentation under its default locations typically requires administrative privileges. Use the command sudo to run the installer script in that case. For example, if the installer is called “installer.sh”, run:

   sudo bash installer.sh
   

   sudo asks you to enter your password on the machine. After providing it, the installation starts. sudo can be omitted when installing to a location for which you have the necessary write permissions.
6. The installer asks whether to proceed with the installation of the documentation as all users of the computer will be able to use it. To install, type “Y”; otherwise, type “n”.

   WARNING: Wolfram Language 13.2. English Documentation is protected by copyright law and international treaties. Unauthorized reproduction or distribution may result in severe civil and criminal penalties and will be prosecuted to the maximum extent under law.
   
   All users of this computer will be able to use this software.
   
   Proceed with installation? (Y/n)
   >
   

The installation is now complete.