Update docs for trpc adapter

[Syarx]

I tried this implementation and it seems to work fine, without the need for the trpc adapter plugin which also seems abandoned

const app = new Elysia()
  .all("/api/trpc/*", async (opts) => {
    const res = await fetchRequestHandler({
      endpoint: "/api/trpc",
      router: appRouter,
      req: opts.request,
      createContext,
    }); 
    return res;
  })

[bibauporto]

I was struggeling with it for a good amount of hours, this solved the issue