Added how to reconfigure a package

knowledge base/apt.md

@@ -51,6 +51,7 @@ sudo apt-mark auto $(sudo apt-mark showmanual)
 
 # Reconfigure packages.
 sudo dpkg-reconfigure 'mariadb-server'
+sudo dpkg-reconfigure -p 'low' 'unattended-upgrades'
 ```
 
 ## Automate security upgrades
@@ -58,6 +59,9 @@ sudo dpkg-reconfigure 'mariadb-server'
 Leverage `unattended-upgrades` for this.
 
 ```sh
+# Configure the packages to keep up to date.
+sudo dpkg-reconfigure -p 'low' 'unattended-upgrades'
+
 # Check what packages would be installed.
 sudo unattended-upgrade -d --dry-run
 
@@ -65,6 +69,19 @@ sudo unattended-upgrade -d --dry-run
 sudo unattended-upgrade
 ```
 
+## Troubleshooting
+
+### Fix a "Problem with MergeList" or "status file could not be parsed" error
+
+> E: Encountered a section with no Package: header
+> E: Problem with MergeList /var/lib/apt/lists/deb.debian.org_debian_dists_bullseye_main_i18n_Translation-en
+> E: The package lists or status file could not be parsed or opened.
+
+```sh
+sudo rm -vrf '/var/lib/apt/lists/'*
+sudo apt update
+```
+
 ## Further readings
 
 - [Apt configuration]
@@ -72,8 +89,13 @@ sudo unattended-upgrade
 - [Unattended Upgrades]
 - [cheat.sh]
 
+## Sources
+
+- [Fix a "Problem with MergeList" or "status file could not be parsed" error]
+
 <!-- external references -->
 [apt configuration]: https://wiki.debian.org/AptConfiguration
 [configuring apt sources]: https://wiki.debian.org/SourcesList
 [unattended upgrades]: https://wiki.debian.org/UnattendedUpgrades
-[cheat.sh]:
+[cheat.sh]: https://cheat.sh/apt
+[fix a "problem with mergelist" or "status file could not be parsed" error]: https://askubuntu.com/questions/30072/how-do-i-fix-a-problem-with-mergelist-or-status-file-could-not-be-parsed-err#30199

knowledge base/dpkg.md

@@ -3,6 +3,9 @@
 ## TL;DR
 
 ```sh
+# Reconfigure a package.
+dpkg-reconfigure --priority low unattended-upgrades
+
 # add an extra architecture
 dpkg --add-architecture i386