Clarify cleanup guideline to specify avoiding try-catch-finally for cleanup in tests

Author: johlju

.github/instructions/dsc-community-style-guidelines-pester.instructions.md

@@ -47,5 +47,5 @@ applyTo: "**/*.[Tt]ests.ps1"
 - Keep results and assertions in same `It` block
 - Cover all scenarios and code paths
 - Use `BeforeEach` and `AfterEach` sparingly
-- Avoid try-catch for cleanup, use `AfterAll` or `AfterEach`
+- Avoid try-catch-finally for cleanup, use `AfterAll` or `AfterEach`
 - Avoid unnecessary remove/recreate cycles