docs: add currentTestName difference (#6145)

docs/guide/migration.md

@@ -331,6 +331,15 @@ Where Jest does it by default, when mocking a module and wanting this mocking to
 server.deps.inline: ["lib-name"]
 ```
 
+### expect.getState().currentTestName
+
+Vitest's `test` names are joined with a `>` symbol to make it easier to distinguish tests from suites, while Jest uses an empty space (` `).
+
+```
+- `${describeTitle} ${testTitle}`
++ `${describeTitle} > ${testTitle}`
+```
+
 ### Envs
 
 Just like Jest, Vitest sets `NODE_ENV` to `test`, if it wasn't set before. Vitest also has a counterpart for `JEST_WORKER_ID` called `VITEST_POOL_ID` (always less than or equal to `maxThreads`), so if you rely on it, don't forget to rename it. Vitest also exposes `VITEST_WORKER_ID` which is a unique ID of a running worker - this number is not affected by `maxThreads`, and will increase with each created worker.