Update installation on debian

the $CODENAME doesn't work properly 

Signed-off-by: Mohammed Abdallah <[email protected]>

Author: mohamedabdallah20

installation/linux/debian.md

@@ -54,7 +54,7 @@ Refer to the [supported platform documentation](../supported-platforms.md) to se
 For Debian, you must add the Fluent Bit APT server entry to your sources lists.
 
 ```bash copy
-echo "deb [signed-by=/usr/share/keyrings/fluentbit-keyring.gpg] https://packages.fluentbit.io/ubuntu/${CODENAME} ${CODENAME} main" | sudo tee /etc/apt/sources.list.d/fluent-bit.list
+echo "deb [signed-by=/usr/share/keyrings/fluentbit-keyring.gpg] https://packages.fluentbit.io/ubuntu/$(grep -oP '(?<=VERSION_CODENAME=).*' /etc/os-release || lsb_release -cs) $(grep -oP '(?<=VERSION_CODENAME=).*' /etc/os-release || lsb_release -cs) main" | sudo tee /etc/apt/sources.list.d/fluent-bit.list
 ```
 
 Replace _`CODENAME`_ with your specific [Debian release name](https://wiki.debian.org/DebianReleases#Production\_Releases) (for example: `bookworm` for Debian 12)