docs: elaboration for resetModules (#3059)

Co-authored-by: Vladimir <sleuths.slews0s@icloud.com>

Author: jonathan-graf

docs/api/vi.md

@@ -291,23 +291,24 @@ test('importing the next module imports mocked one', async () => {
 
 - **Type**: `() => Vitest`
 
-  Resets modules registry by clearing cache of all modules. Might be useful to isolate modules where local state conflicts between tests.
+  Resets modules registry by clearing cache of all modules. This allows modules to be reevaluated when reimported. Top-level imports cannot be reevaluated. Might be useful to isolate modules where local state conflicts between tests.
 
   ```ts
   import { vi } from 'vitest'
+  import { data } from './data.js' // Will not get reevaluated beforeEach test
 
-  beforeAll(() => {
+  beforeEach(() => {
     vi.resetModules()
   })
 
   test('change state', async () => {
-    const mod = await import('./some/path')
+    const mod = await import('./some/path.js') // Will get reevaluated
     mod.changeLocalState('new value')
     expect(mod.getLocalState()).toBe('new value')
   })
 
   test('module has old state', async () => {
-    const mod = await import('./some/path')
+    const mod = await import('./some/path.js') // Will get reevaluated
     expect(mod.getLocalState()).toBe('old value')
   })
   ```