chore: add line numbers to flow link in compiler readme

Author: yyx990803

Diff for: packages/vue-template-compiler/README.md

@@ -39,7 +39,7 @@ The optional `options` object can contain the following:
 
 - `modules`
 
-  An array of compiler modules. For details on compiler modules, refer to the `ModuleOptions` type in [flow declarations](https://github.com/vuejs/vue/blob/dev/flow/compiler.js) and the [built-in modules](https://github.com/vuejs/vue/tree/dev/src/platforms/web/compiler/modules).
+  An array of compiler modules. For details on compiler modules, refer to the `ModuleOptions` type in [flow declarations](https://github.com/vuejs/vue/blob/dev/flow/compiler.js#L38-L45) and the [built-in modules](https://github.com/vuejs/vue/tree/dev/src/platforms/web/compiler/modules).
 
 - `directives`