docs/release-notes: update for release 0.26.0

Author: prestist

docs/release-notes.md

@@ -4,7 +4,20 @@ nav_order: 8
 
 # Release notes
 
-## Upcoming coreos-installer 0.26.0 (unreleased)
+## Upcoming coreos-installer 0.27.0 (unreleased)
+
+Major changes:
+
+
+Minor changes:
+
+
+Internal changes:
+
+
+Packaging changes:
+
+## Upcoming coreos-installer 0.26.0 (2026-02-27)
 
 Major changes:
 
@@ -20,6 +33,8 @@ Internal changes:
 
 Packaging changes:
 
+- Bump minimum supported Rust version (MSRV) to 1.85.0
+
 ## coreos-installer 0.25.0 (2025-09-29)
 
 Major changes: