Nested route with HonoJS should have better documentations

I just get confused as a 🔥Hono user. My issue is in the comment in the code.

```ts
const api = new Hono();
const openapi = fromHono(api, {
// only use "base" option if schema.servers do not append nested route, like "https://api.example.com"
// and okay with /v1/ everywhere on the Swagger UI
// base: "/v1",

// but here it is okay either use "/docs" or "docs",
docs_url: "/docs",

// must not use the default "/openapi.json" will not work
openapi_url: 'openapi.json',
schema: {
servers: [
{
// this must be set and the append the nested route, or "Try it out" button will break
url: 'https://api.example.com/v1',
}
]
}
});

// the final url for this endpoint will be "https://api.example.com/v1/api/tasks"
openapi.get("/api/tasks", TaskList);

const app = new Hono();
app.route('/v1', api);
```

Start with the fromHono configuration and the nested app.route('/v1', api) example shown in the issue. Document how docs_url, openapi_url, schema.servers, and the nested route combine, including the resulting endpoint URL and the conditions that keep Swagger UI's Try it out working.

Written by the indexing model from the issue text.