[MCO-1914] Enhacement of the MCO OS streams feature

This commit adds the formal enhancement proposal for MCO-1914.

This feature adds the ability to run multiple OS base images
simultaneously in a cluster by allowing users to select an image
'stream' on a per-MCP basis.

Author: pablintino

enhancements/machine-config/os-images-streams.md

@@ -0,0 +1,124 @@
+---
+title: machine-config-os-images-streams
+authors:
+  - "@pablintino"
+reviewers:
+  - "@yuqi-zhang"
+approvers:
+  - "@yuqi-zhang"
+api-approvers:
+  - "@JoelSpeed"
+creation-date: 2025-10-24
+tracking-link:
+  - https://issues.redhat.com/browse/MCO-1914
+see-also:
+replaces:
+superseded-by:
+---
+
+# MachineConfig OS Images Streams
+
+## Summary
+
+This enhancement allows administrators to easily assign different OS images
+to specific groups of nodes using a simple "stream" identifier.
+
+It introduces a new, optional stream field in theMCP. When this field is set,
+the MCO will provision nodes in that pool using the specific OS image 
+associated with that stream name.
+
+This provides a simple, declarative way to run different OS variants within
+the same cluster. This can be used to test new major OS versions 
+(like RHEL 10) on a subset of nodes or to deploy specialized images,
+without affecting the rest of the cluster.
+
+## Motivation
+
+**TBD**
+
+
+### User Stories
+
+**TBD**
+
+### Goals
+
+**TBD**
+
+### Non-Goals
+
+**TBD**
+
+## Proposal
+
+**TBD**
+
+### API Extensions
+
+**TBD**
+
+### Topology Considerations
+
+**TBD**
+
+### Implementation Details/Notes/Constraints
+
+**TBD**
+
+### Risks and Mitigations
+
+**TBD**
+
+### Drawbacks
+
+**TBD**
+
+## Design Details
+
+### Open Questions [optional]
+
+None.
+
+## Test Plan
+
+**TBD**
+
+## Graduation Criteria
+
+**TBD**
+
+### Dev Preview -> Tech Preview
+
+**TBD**
+
+### Tech Preview -> GA
+
+**TBD**
+
+### Removing a deprecated feature
+
+## Upgrade / Downgrade Strategy
+
+**TBD**
+
+## Version Skew Strategy
+
+**TBD**
+
+## Operational Aspects of API Extensions
+
+#### Failure Modes
+
+**TBD**
+
+## Support Procedures
+
+None.
+
+## Implementation History
+
+Not applicable.
+
+## Alternatives (Not Implemented)
+
+**TBD**