[Documentation] README: load function missing "intent"

[Brendan-csel]

In the README Load Functions section the params table doesn't include the intent parameter

As its only argument, the load function is passed an object that you can use to access route information

Perhaps something like: intent indicates why load was called:

• "initial" - the route is being initially shown (ie page load??).
• "native" - navigate originated from the browser (eg back/forward).
• "navigate" - navigate originated from the router (eg call to navigate or anchor clicked).
• "preload" - not navigating, just preloading (eg link hover).