Clarify SchemaId GetHashCode scope in XML docs

Agent-Logs-Url: https://github.com/fsprojects/FSharp.Data.GraphQL/sessions/70eb1609-2aab-4948-8d69-52c900443420

Co-authored-by: xperiandri <2365592+xperiandri@users.noreply.github.com>

Author: Copilot

src/FSharp.Data.GraphQL.Shared/ValidationResultCache.fs

@@ -17,9 +17,10 @@ type IValidationResultCache =
 module SchemaId =
     /// <summary>
     /// Computes an in-memory schema identifier from an introspection schema instance.
+    /// This identifier is valid only within the current process/runtime and is not deterministic across process restarts.
     /// </summary>
     /// <param name="introspectionSchema">The introspection schema.</param>
-    /// <returns>A string representation of the schema hash code.</returns>
+    /// <returns>A string representation of the schema hash code for in-process cache keys.</returns>
     [<CompiledName("FromIntrospectionSchema")>]
     let fromIntrospectionSchema (introspectionSchema : IntrospectionSchema) =
         introspectionSchema.GetHashCode().ToString(System.Globalization.CultureInfo.InvariantCulture)