docs: use unpinned python3-dev in setup instructions

python3.12-dev doesn't exist on releases whose default Python isn't 3.12
(e.g. Ubuntu Resolute), so the install command failed there. python3-dev
pulls the correct dev headers for the running release's default Python
(3.13 on Resolute/Trixie, 3.12 on Noble, ...). Fixed in README.md and
DOCUMENTATION.md.

Signed-off-by: Igor Pecovnik <igor@armbian.com>

Author: igorpecovnik

DOCUMENTATION.md

@@ -50,7 +50,7 @@ Ensure you have Python and the necessary development packages installed:
 
 ```bash
 sudo apt-get update
-sudo apt-get install python3 python3-pip python3-venv python3.12-dev
+sudo apt-get install python3 python3-pip python3-venv python3-dev
 ```
 
 If using Debian, you may need to install the following packages for `mkdocs-material`:

README.md

@@ -14,7 +14,7 @@ However, to **enjoy a fully rendered local preview** with proper styling and liv
 
 ```bash
 sudo apt-get update
-sudo apt-get install python3 python3-pip python3-venv python3.12-dev
+sudo apt-get install python3 python3-pip python3-venv python3-dev
 ```
 
 If using Debian, you may need to install the following packages for `mkdocs-material`: