Change link to relative (vuejs#890)

Author: Alex-Sokolov

src/v2/guide/render-function.md

@@ -478,7 +478,7 @@ Everything the component needs is passed through `context`, which is an object c
 - `data`: The entire data object passed to the component
 - `parent`: A reference to the parent component
 - `listeners`: (2.3.0+) An object containing parent-registered event listeners. This is simply an alias to `data.on`
-- `injections`: (2.3.0+) if using the [`inject`](https://vuejs.org/v2/api/#provide-inject) option, this will contain resolved injections.
+- `injections`: (2.3.0+) if using the [`inject`](../api/#provide-inject) option, this will contain resolved injections.
 
 After adding `functional: true`, updating the render function of our anchored heading component would simply require adding the `context` argument, updating `this.$slots.default` to `context.children`, then updating `this.level` to `context.props.level`.