nrt: doc: document the new attributes format

Since we are moving to a more structured format, let's
document the expectations.

Signed-off-by: Francesco Romani <[email protected]>

Author: ffromani

pkg/noderesourcetopology/README.md

@@ -155,6 +155,27 @@ Should the cluster need to have different settings (e.g. topology manager) or NU
 using [affinity](https://kubernetes.io/docs/user-guide/node-selection/#node-affinity-beta-feature) or also
 [taints](https://kubernetes.io/docs/user-guide/node-selection/#taints-and-toleations-beta-feature).
 
+#### Topology Manager configuration
+
+***Target audience: developers and operators of topology updaters (NodeResourceTopology producers)***
+
+In addition to logically partitioning a cluster like explained above, the topology-aware scheduler needs to know key node-specific configuration settings like Topology manager policy and scope.
+This data is expected to be provided as top-level `Attributes` of the NodeResourceTopology objects:
+
+NodeResourceTopology producers should add top-level `Attributes` in the following format
+- For `Name` and `Value` of attributes, words should be `snakeCase`
+- The `Name` of each attribute should be **the same of the corresponding kubelet configuration option**.
+  - example: `--topology-manager-scope` becomes `topologyManagerScope`
+  - example: `topologyManagerPolicy` becomes `topologyManagerPolicy`
+- The `Value` of each attribute should be **one of the value of the corresponding kubelet configuration option, VERBATIM**.
+  - example: `single-numa-node` becomes `single-numa-node`
+- Should `topologyManagerOptions` be exposed:
+  - they should be expanded in key-value pairs, using the `String()` representation
+  - each key-value pair should be preceded by the `topologyManagerOption` prefix
+  - every other provision described above applies
+  - example: the `prefer-closest-numa-nodes` option becomes `topologyManagerOptionPreferClosestNumaNodes`, accepting exactly one of either `true` and `false`.
+  - **RATIONALE**: this representation wants to guarantee all the Attribute Names are unique (no aliasing). It must be noted this is a stricter requirement with respect to the Attribute representation
+    in NRT objects, and this requirement could be lifted in the future (an upgrade path will be provided).
 
 ### Demo