uses 'findComponent' to find components instead of 'find' (#1656)

Co-authored-by: Michael Haak <[email protected]>

Author: wabuMike

docs/guides/common-tips.md

@@ -142,7 +142,7 @@ import ChildComponent from '@/components/ChildComponent'
 describe('ParentComponent', () => {
   it("displays 'Emitted!' when custom event is emitted", () => {
     const wrapper = mount(ParentComponent)
-    wrapper.find(ChildComponent).vm.$emit('custom')
+    wrapper.findComponent(ChildComponent).vm.$emit('custom')
     expect(wrapper.html()).toContain('Emitted!')
   })
 })