feat(docs): document Resource Mapping Groups and FQN format

docs/components/policy/resource_mappings.md

@@ -6,11 +6,65 @@ A Resource Mapping contains:
 
 1. An associated `attribute value`.
 2. A set of related `terms`.
+3. An optional `group` (see [Resource Mapping Groups](#resource-mapping-groups) below).
 
 The primary consumer of a Resource Mapping is a Policy Decision Point (PDP), which processes data, applies logic using the known terms, and relies on them to map the data to Attribute Values. By mapping a set of terms to a given attribute value, a Policy Enforcement Point (PEP) can properly apply the TDF to the resource data using the appropriate attribute values.
 
-# Examples
+## Examples
 
-Alice is a system administrator. She defines an Attribute definition called color with values like red, green, blue, purple, etc. For the Attribute Value `https://demo.com/attr/color/value/purple'`, she would define a Resource Mapping for processing data that may involve terms like `indigo`, `lilac`, `plum`, or `lavender`.
+Alex is a system administrator. They define an Attribute definition called color with values like red, green, blue, purple, etc. For the Attribute Value `https://demo.com/attr/color/value/purple`, they would define a Resource Mapping for processing data that may involve terms like `indigo`, `lilac`, `plum`, or `lavender`.
 
-Bob is a system administrator in the US Department of Defense (DoD). Bob defines a hierarchical attribute called classification with values of `topsecret`, `secret`, `confidential`, and `unclassified`. He needs to create a resource mapping that defines a normalization of the various short forms and acronyms that map to each of these classification levels. For the `topsecret` attribute value, he might include terms like `ts`, `top secret`, and `top-secret`. Whereas for unclassified he might include `u`, `uc`, or other variations.
+Beth is a system administrator in the US Department of Defense (DoD). Beth defines a hierarchical attribute called classification with values of `topsecret`, `secret`, `confidential`, and `unclassified`. She needs to create a resource mapping that defines a normalization of the various short forms and acronyms that map to each of these classification levels. For the `topsecret` attribute value, she might include terms like `ts`, `top secret`, and `top-secret`. Whereas for unclassified she might include `u`, `uc`, or other variations.
+
+## Resource Mapping Groups
+
+Resource Mapping Groups organize multiple Resource Mappings into logical collections under a [Namespace](./attributes.md#namespaces). Groups allow you to manage sets of related mappings together, which is useful when resources share common access controls or need to be managed as a unit.
+
+A Resource Mapping Group contains:
+
+1. A **name** identifying the group.
+2. A **namespace** that the group belongs to.
+3. A **Fully Qualified Name (FQN)** derived from the namespace and group name.
+
+### FQN Format
+
+Each Resource Mapping Group has a unique FQN following this pattern:
+
+```text
+https://<namespace>/resm/<group-name>
+```
+
+For example, a group named `ntk` under the namespace `example.org` would have the FQN:
+
+```text
+https://example.org/resm/ntk
+```
+
+Like other FQN'd objects in the platform, Resource Mapping Group FQNs are normalized to lower case.
+
+:::note FQN visibility in the CLI
+The `otdfctl` CLI does not currently display the FQN when listing or getting Resource Mapping Groups. To determine a group's FQN, construct it from the namespace and group name using the format above.
+:::
+
+### Creating a Group and Assigning Mappings
+
+Groups are created under a namespace, and individual Resource Mappings can be assigned to a group at creation or update time. Building on Beth's classification example from above:
+
+```bash
+# Create a resource mapping group for classification terms under Beth's namespace
+otdfctl policy resource-mapping-groups create \
+  --namespace-id <bobs-namespace-id> \
+  --name classification
+
+# Create a resource mapping for "topsecret" terms, assigned to the group
+otdfctl policy resource-mappings create \
+  --attribute-value-id <topsecret-value-id> \
+  --terms "ts,top secret,top-secret" \
+  --group-id <classification-group-id>
+```
+
+This group's FQN would be `https://<bobs-namespace>/resm/classification`, and it can be referenced by that FQN to resolve all classification term mappings from the database.
+
+### Using Groups as Synonym Dictionaries
+
+A Resource Mapping Group's FQN can be used as a synonym dictionary identifier in systems that resolve term-to-attribute-value mappings. When referenced by FQN, the system retrieves all Resource Mappings within that group from the policy database, enabling database-backed synonym resolution rather than inline configuration.