Update description of CDI dirs

This change improves the description of the CDI spec directories.
The support for YAML files is called out and the exact file
extensions are mentioned.

Signed-off-by: Evan Lezar <[email protected]>

Author: elezar

README.md

@@ -51,14 +51,15 @@ to duplication of the functionality in higher-level abstractions (such as
 
 For CDI to work the following needs to be done:
 
-- CDI file containing updates for the OCI spec in JSON format should be present
-  in the CDI spec directory. Default directories are `/etc/cdi` and
-  `/var/run/cdi`
-- Fully qualified device name should be passed to the runtime either using
-  command line parameters for podman or using container annotations for CRI-O
-  and containerd
-- Container runtime should be able to find the CDI file by the device name and
-  update the container config using CDI file content.
+- CDI file containing updates for the OCI spec in JSON or YAML format (with a
+  `.json` or `.yaml` file extension, respectively) should be present in a CDI
+  spec directory. The default directories are `/etc/cdi` and `/var/run/cdi`, but
+  may depend on your runtime configuration
+- One or more fully-qualified device names should be passed to the runtime
+  either using command line parameters for CLI tools such as podman or Docker,
+  or using container annotations or CRI fields for CRI-O and containerd
+- The container runtime should be able to find the CDI file by the device name
+  and update the container config using CDI file content.
 
 ## How to configure CDI?