Add retraction notice to salvage proposal

Added a retraction notice for the salvage proposal due to author concerns and lack of implementation plans.

Author: Princess-Cheeseballs

src/en/space-station-14/departments/cargo/proposals/salvage-proposal.md

@@ -1,5 +1,12 @@
 # Salvage
 
+```admonish warning "Retracted"
+This content was requested to be retracted by its authors due to the following:
+- Majority of authors no longer work on upstream
+- Majority of authors no longer believe salvage can work upstream
+- No current plants to implement this doc
+```
+
 | Designers                      | Implemented | GitHub Links |
 |--------------------------------|---|---|
 | EmoGarbage, Emisse, Mirrorcult | :warning: Partially | TBD |
@@ -210,4 +217,4 @@ Unlike tech disks or similar items that sci uses, blueprints are restricted to a
 This means things like mining charges, fultons, flares, etc.
 
 The intent for blueprints is to give salvage a reward in being able to replenish their own stockpiles of consumables quickly.
-It also adds variation between rounds as certain items become far more available than others as salvage unlocks blueprints at different times.
+It also adds variation between rounds as certain items become far more available than others as salvage unlocks blueprints at different times.