docs: Add containerd install guide

Create a containerd installation guide and a new `kata-manager` script
for 2.0 that automated the steps outlined in the guide.

Also cleaned up and improved the installation documentation in various
ways, the most significant being:

- Added legacy install link for 1.x installs.
- Official packages section:
  - Removed "Contact" column (since it was empty!)
  - Reworded "Versions" column to clarify the versions are a minimum
    (to reduce maintenance burden).
  - Add a column to show which installation methods receive automatic updates.
  - Modified order of installation options in table and document to
    de-emphasise automatic installation and promote official packages
    and snap more.
- Removed sections no longer relevant for 2.0.

Fixes: #738.

Signed-off-by: James O. D. Hunt <james.o.hunt@intel.com>

docs/install/container-manager/containerd/containerd-install.md

@@ -0,0 +1,128 @@
+# Install Kata Containers with containerd
+
+> **Note:**
+>
+> - If Kata Containers and / or containerd are packaged by your distribution,
+>   we recommend you install these versions to ensure they are updated when
+>   new releases are available.
+
+> **Warning:**
+>
+> - These instructions install the **newest** versions of Kata Containers and
+>   containerd from binary release packages. These versions may not have been
+>   tested with your distribution version.
+>
+> - Since your package manager is not being used, it is **your**
+>   responsibility to ensure these packages are kept up-to-date when new
+>   versions are released.
+>
+> - If you decide to proceed and install a Kata Containers release, you can
+>   still check for the latest version of Kata Containers by running
+>   `kata-runtime kata-check --only-list-releases`.
+>
+> - These instructions will not work for Fedora 31 and higher since those
+>   distribution versions only support cgroups version 2 by default. However,
+>   Kata Containers currently requires cgroups version 1 (on the host side). See
+>   https://github.com/kata-containers/kata-containers/issues/927 for further
+>   details.
+
+## Install Kata Containers
+
+> **Note:**
+>
+> If your distribution packages Kata Containers, we recommend you install that
+> version. If it does not, or you wish to perform a manual installation,
+> continue with the steps below.
+
+- Download a release from:
+
+  - https://github.com/kata-containers/kata-containers/releases
+
+  Note that Kata Containers uses [semantic versioning](https://semver.org) so
+  you should install a version that does *not* include a dash ("-"), since this
+  indicates a pre-release version.
+
+- Unpack the downloaded archive.
+
+   Kata Containers packages use a `/opt/kata/` prefix so either add that to
+   your `PATH`, or create symbolic links for the following commands. The
+   advantage of using symbolic links is that the `systemd(1)` configuration file
+   for containerd will not need to be modified to allow the daemon to find this
+   binary (see the [section on installing containerd](#install-containerd) below).
+
+   | Command | Description |
+   |-|-|
+   | `/opt/kata/bin/containerd-shim-kata-v2` | The main Kata 2.x binary |
+   | `/opt/kata/bin/kata-collect-data.sh`    | Data collection script used for [raising issues](https://github.com/kata-containers/kata-containers/issues) |
+   | `/opt/kata/bin/kata-runtime`            | Utility command |
+
+- Check installation by showing version details:
+
+   ```bash
+   $ kata-runtime --version
+   ```
+
+## Install containerd
+
+> **Note:**
+>
+> If your distribution packages containerd, we recommend you install that
+> version. If it does not, or you wish to perform a manual installation,
+> continue with the steps below.
+
+- Download a release from:
+
+  - https://github.com/containerd/containerd/releases
+
+- Unpack the downloaded archive.
+
+- Configure containerd
+
+  - Download the standard `systemd(1)` service file and install to
+    `/etc/systemd/system/`:
+
+    - https://raw.githubusercontent.com/containerd/containerd/master/containerd.service
+
+    > **Notes:**
+    >
+    > - You will need to reload the systemd configuration after installing this
+    >   file.
+    >
+    > - If you have not created a symbolic link for
+    >   `/opt/kata/bin/containerd-shim-kata-v2`, you will need to modify this
+    >   file to ensure the containerd daemon's `PATH` contains `/opt/kata/`.
+    >   See the `Environment=` command in `systemd.exec(5)` for further
+    >   details.
+
+  - Add the Kata Containers configuration to the containerd configuration file:
+
+    ```toml
+    [plugins]
+        [plugins.cri]
+            [plugins.cri.containerd]
+            default_runtime_name = "kata"
+
+            [plugins.cri.containerd.runtimes.kata]
+            runtime_type = "io.containerd.kata.v2"
+    ```
+
+    > **Note:**
+    >    
+    > The containerd daemon needs to be able to find the
+    > `containerd-shim-kata-v2` binary to allow Kata Containers to be created.
+
+  - Start the containerd service.
+
+## Test the installation
+
+You are now ready to run Kata Containers. You can perform a simple test by
+running the following commands:
+
+```bash
+$ image="docker.io/library/busybox:latest"
+$ sudo ctr image pull "$image"
+$ sudo ctr run --runtime "io.containerd.kata.v2" --rm -t "$image" test-kata uname -r
+```
+
+The last command above shows details of the kernel version running inside the
+container, which will likely be different to the host kernel version.