Fix HybridCache immutability documentation - require both conditions for object reuse (#36029)

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Co-authored-by: copilot-swe-agent[bot] <[email protected]>
Co-authored-by: tdykstra <[email protected]>

Author: Copilot

aspnetcore/performance/caching/hybrid.md

@@ -210,7 +210,7 @@ Because much `HybridCache` usage will be adapted from existing `IDistributedCach
 * They're immutable types.
 * The code doesn't modify them.
 
-In such cases, inform `HybridCache` that it's safe to reuse instances by making at least one of the following changes:
+In such cases, inform `HybridCache` that it's safe to reuse instances by making both of the following changes:
 
 * Marking the type as `sealed`. The `sealed` keyword in C# means that the class can't be inherited.
 * Applying the `[ImmutableObject(true)]` attribute to the type. The `[ImmutableObject(true)]` attribute indicates that the object's state can't be changed after it's created.

aspnetcore/release-notes/aspnetcore-9/includes/hybrid-cache.md

@@ -114,7 +114,7 @@ Because a lot of `HybridCache` usage will be adapted from existing `IDistributed
 * If the types being cached are immutable.
 * If the code doesn't modify them.
 
-In such cases, inform `HybridCache` that it's safe to reuse instances by:
+In such cases, inform `HybridCache` that it's safe to reuse instances by making both of the following changes:
 
 * Marking the type as `sealed`. The `sealed` keyword in C# means that the class can't be inherited.
 * Applying the `[ImmutableObject(true)]` attribute to it. The `[ImmutableObject(true)]` attribute indicates that the object's state can't be changed after it's created.