Move last step to first step in release requirements

Author: elenatanasoiu

extensions/ql-vscode/docs/test-plan.md

@@ -9,10 +9,10 @@ effort vs value basis).
 We don't need to test features (and permutations of features) that are covered by automated tests.
 
 ### Before releasing the VS Code extension
+- Go through the required test cases listed below
 - Check major PRs since the previous release for specific one-off things to test. Based on that, you might want to 
 choose to go through some of the Optional Test Cases.
 - Run a query using the existing version of the extension (to generate an “old” query history item)
-- Go through the required test cases listed below
 
 ## Required Test Cases