change layout for better management

- instead of just `syspkgs` and `srcpkgs` add more lists
  - `appimages`, `flatpkgs` and others as they come up

CONTRIBUTING.md

@@ -0,0 +1,52 @@
+# Contributing
+
+## Package definition
+
+Package defintions are just `yaml` tasks in the directory
+`tasks/pkgs`, which handle how a package is installed.
+
+Most can be installed using the `syspkgs` list, and are simply
+appending the package name to said list based on the system.
+
+If a package can be installed via an entry to `syspkgs` for some,
+but not all platforms, handling is done to either inform the user
+that the package is not available, or to append the package name
+to another installation method such as:
+
+- `appimages` to install the appimage of a package
+- `cargopkgs` to install via the rust cargo package manager
+- `cargoversioned` to install version lockec cargo packages
+- `caskpkgs` to install a homebrew cask
+- `flatpkgs` to install flatpaks
+- `gopkgs` to install using the `go install` command
+- `npmpkgs` to install packages from npm
+- `pipxpkgs` to install packages from Python pip
+- `srcpkgs` to build packages from source
+- `tappkgs` to install packages from home brew taps
+
+Alternative sources of packages can be defined with entries to:
+
+- `fpremotes` to add a flatpak remote
+- `brewtaps` to add a homebrew tap
+
+### Adding system level repositories
+
+Many packages exist in their own external repository for the
+given system, such as `/etc/yum.repos.d` for RedHat based linux
+distros, `/etc/apt/sources.list.d` for Debian based distros and
+others. Since you an add the package to `syspkgs` by enabling a
+repo, the coresponding task in `tasks/pkgs` should take the
+steps needed to enable the repository.
+
+### Packages with multiple instllation methods
+
+Many packages can be installed in different ways, like the
+`bitwarden` package. `bitwarden` can be installed as a `syspkg`
+on some machines, a `caskpkg` on macOS, an `appimage`, a `flatpak`
+or even a `snap`.
+
+For such packages, a default is chosen to install, in the following order
+of precedence: `syspkgs`, `flatpkgs`, `snappkgs`, `appimages`.
+
+In that order, `syspkgs` and `caskpkgs` have equal weight, as it applies
+to macOS.