Update composition-api-introduction.md (#832)

Alex-Sokolov · web-flow · commit e7c380d24b7d · 2021-01-30T22:06:34.000+01:00
diff --git a/src/guide/composition-api-introduction.md b/src/guide/composition-api-introduction.md
@@ -309,7 +309,7 @@ export default {
 }
 ```
 
-For more details on `watch`, refer to our [in-depth guide]().
+For more details on `watch`, refer to our [in-depth guide](reactivity-computed-watchers.md#watch).
 
 **Let’s now apply it to our example:**
 

Original file line number	Diff line number	Diff line change
`@@ -309,7 +309,7 @@ export default {`
`309`	`309`	`}`
`310`	`310`	```
`311`	`311`
`312`		-For more details on `watch`, refer to our [in-depth guide]().
	`312`	+For more details on `watch`, refer to our [in-depth guide](reactivity-computed-watchers.md#watch).
`313`	`313`
`314`	`314`	`Let’s now apply it to our example:`
`315`	`315`