linux: added appimage

wiki/linux/appimage.md

@@ -0,0 +1,21 @@
+# AppImage
+
+[AppImage](https://appimage.org/) is a portable Linux application format that allows programs to
+run without being installed through a traditional package manager.
+
+## Usage
+
+This section addresses the usage of AppImage files.
+
+### Running and Installing AppImage Files
+
+This section is based on an
+[article by Sujit Kumar](https://dev.to/sujit-shrc/install-appimages-on-arch-based-linux-lm2).
+
+AppImages are executed directly as standalone binaries.
+To start an application make the AppImage executable using the following command.
+`<appimage-path>` is the path to the AppImage file.
+
+```sh
+chmod +x <appimage-path>
+```

wiki/linux/package_manager.md

@@ -1,6 +1,8 @@
 # Package Manager
 
-Package managers are important programs to get software onto your system.
+Package managers are used to handle the installation and management of programs on systems.
+
+## List of Package Managers
 
 The following is a list of package managers and the corresponding [Linux](/wiki/linux.md)
 distributions.
@@ -9,4 +11,14 @@ distributions.
   [Proxmox](/wiki/linux/proxmox.md) use the [APT](/wiki/linux/package_manager/apt.md) package
   manager.
 - [Arch Linux](/wiki/linux/arch-linux.md) and Arch-based distributions use
-  [Pacman]() and various managers for the AUR.
+  [Pacman](/wiki/linux/package_manager/pacman_and_aur.md) and various managers for the AUR.
+
+## Alternative Software Distribution Formats
+
+Besides traditional package managers, there are portable or universal application formats that work
+across distributions.
+These formats are not package managers.
+They distribute standalone applications that can run independently of the system package database.
+
+- [AppImage](/wiki/linux/appimage.md)
+- [Flatpak](/wiki/linux/flatpak.md)