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>

utils/README.md

@@ -0,0 +1,55 @@
+# Utilities
+
+# Kata Manager
+
+> **Warning:**
+>
+> - Kata Manager 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.
+
+> **Note:**
+>
+> We recommend users install Kata Containers using
+> [official distribution packages](../docs/install/README.md#official-packages), where available.
+
+The [`kata-manager.sh`](kata-manager.sh) script automatically installs and
+configures Kata Containers and containerd.
+
+This scripted method installs the latest versions of Kata Containers and
+containerd. However, be aware of the following before proceeding:
+
+- Packages will **not** be automatically updated
+
+  Since a package manager is not being used, it is **your** responsibility
+  to ensure these packages are kept up-to-date when new versions are released
+  to ensure you are using a version that includes the latest security and bug fixes.
+
+- Potentially untested versions or version combinations
+
+  This script installs the *newest* versions of Kata Containers
+  and containerd from binary release packages. These versions may
+  not have been tested with your distribution version.
+
+If you still wish to continue, but prefer a manual installation, see
+[the containerd installation guide](/docs/install/container-manager/containerd/containerd-install.md).
+
+## Install a minimal Kata Containers system
+
+To install and configure a system with Kata Containers and containerd, run:
+
+```bash
+$ bash -c "$(curl -fsSL https://raw.githubusercontent.com/kata-containers/kata-containers/2.0-dev/utils/kata-manager.sh)"
+```
+
+> **Notes:**
+>
+> - The script must be run on a system that does not have Kata Containers or
+>   containerd already installed on it.
+>
+> - The script accepts up to two parameters which can be used to test
+>   pre-release versions (a Kata Containers version, and a containerd
+>   version). If either version is unspecified or specified as `""`, the
+>   latest official version will be installed.