Add docs for noscroll

Author: Jayphen

site/content/docs/03-client-api.md

@@ -27,7 +27,9 @@ sapper.start({
 ### goto(href, options?)
 
 * `href` — the page to go to
-* `options` — can include a `replaceState` property, which determines whether to use `history.pushState` (the default) or `history.replaceState`. Not required
+* `options` - not required
+  * `replaceState` (`boolean`, default `false`) — determines whether to use `history.pushState` (the default) or `history.replaceState`.
+  * `noscroll` (`boolean`, default `true`) — whether to scroll to the top of the viewport (0,0) after navigation.
 
 Programmatically navigates to the given `href`. If the destination is a Sapper route, Sapper will handle the navigation, otherwise the page will be reloaded with the new `href`. In other words, the behaviour is as though the user clicked on a link with this `href`.
 

site/content/docs/08-link-options.md

@@ -31,3 +31,15 @@ Adding a `rel=external` attribute to a link...
 ```
 
 ...will trigger a browser navigation when the link is clicked.
+
+### sapper-noscroll
+
+When navigating to internal links, Sapper will change the scroll position to 0,0 so that the user is at the very top left of the page. When a hash is defined, it will scroll to the element with a matching ID.
+
+In certain cases, you may wish to disable this behaviour. Adding a `sapper-noscroll` attribute to a link...
+
+```html
+<a href='path' sapper-noscroll>Path</a>
+```
+
+...will prevent scrolling after the link is clicked.