Document relibc overlay preservation flow

Explain how the rebuilt relibc proof and durable local patch carriers fit together so future upstream refreshes can reapply the compatibility work without relying on nested source state.

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

local/docs/RELIBC-IPC-ASSESSMENT-AND-IMPROVEMENT-PLAN.md

@@ -92,6 +92,11 @@ tree”. It is now proven as an overlay workflow:
 3. rebuild relibc
 4. rebuild real downstream consumers (`libwayland`, `qtbase`)
 
+For the current tree, that overlay story now includes the tracked
+`local/patches/relibc/redox.patch` carrier owning the bounded interface-enumeration and
+resolver-header compatibility deltas (`ifaddrs` / `net_if`, `arpa/nameser.h`, `resolv.h`) rather
+than leaving those as standalone transient patch files.
+
 ## Scope Map
 
 ### In scope in relibc today