Mention using Dispose(Async) to reset context state when pooling

[AndriySvyryd]

---

Document Details

⚠ Do not edit this section. It is required for docs.microsoft.com ➟ GitHub issue linking.

• ID: e638463f-fec2-ca39-37a4-b3580fa874d8
• Version Independent ID: e96b453f-0256-8bc9-bd21-1343f2fe246c
• Content: Advanced Performance Topics
• Content Source: entity-framework/core/performance/advanced-performance-topics.md
• Product: entity-framework
• Technology: entity-framework-core
• GitHub Login: @roji
• Microsoft Alias: avickers