docs: promote proxy extensions to beta (#22361)

Signed-off-by: reggie-k <[email protected]>

Author: reggie-k

docs/developer-guide/extensions/proxy-extensions.md

@@ -1,8 +1,8 @@
 # Proxy Extensions
 
-!!! warning "Alpha Feature (Since 2.7.0)"
-    This is an experimental, [alpha-quality](https://github.com/argoproj/argoproj/blob/main/community/feature-status.md#alpha)
-    feature. It may be removed in future releases or modified in backwards-incompatible ways.
+!!! warning "Beta Feature (Since 2.7.0)"
+    This feature is in the [Beta](https://github.com/argoproj/argoproj/blob/main/community/feature-status.md#beta) stage. 
+    It is generally considered stable, but there may be unhandled edge cases.
 
 ## Overview
 

docs/operator-manual/feature-maturity.md

@@ -17,7 +17,7 @@ to indicate their stability and maturity. These are the statuses of non-stable f
 | Feature                                   | Introduced | Status |
 |-------------------------------------------|------------|--------|
 | [AppSet Progressive Syncs][2]             | v2.6.0     | Alpha  |
-| [Proxy Extensions][3]                     | v2.7.0     | Alpha  |
+| [Proxy Extensions][3]                     | v2.7.0     | Beta   |
 | [Skip Application Reconcile][4]           | v2.7.0     | Alpha  |
 | [AppSets in any Namespace][5]             | v2.8.0     | Beta   |
 | [Cluster Sharding: round-robin][6]        | v2.8.0     | Alpha  |