Fix an error on the document:

[YuJianrong]

param value should be string instead of number

[posva]

Thanks for this. I'm not sure we want to force users pass strings. I do think params should be normalised though

[YuJianrong]

@posva Em... I think maybe it's better to force the user to use string for the router params, consider:

1. When the param is part of the url, like /abc/123 for router /abc/:id, the id will be a string instead of number, it may not be a good idea for the user to pass the param as a number pragmatically.
2. The param member is defined as string in the TypeScript description file so set the param as a number is conflict with the description router.d.ts:

export interface Route {
  path: string;
  name?: string;
  hash: string;
  query: Dictionary<string>;
  params: Dictionary<string>; // <- this one
  fullPath: string;
  matched: RouteRecord[];
  redirectedFrom?: string;
  meta?: any;
}