Tutorial installation instructions didn't work

The instructions at https://docs.servant.dev/en/stable/tutorial/install.html failed for me in multiple ways.

## cabal-install

The `cabal new-build tutorial` command failed, saying

/home/mjd/src/haskell-job/servant/cabal.project:59:
Parse of field 'allow-newer' failed.

I figured out that this was because the Ubuntu Cabal package is from the stone age and installed cabal-3.4. But it still failed:

```
Resolving dependencies...
cabal: Could not resolve dependencies:
[__0] trying: cookbook-basic-auth-0.1 (user goal)
[__1] trying: base-4.9.1.0/installed-4.9.1.0 (dependency of
cookbook-basic-auth)
[__2] next goal: servant-auth (user goal)
[__2] rejecting: servant-auth-0.4.1.0 (conflict:
base==4.9.1.0/installed-4.9.1.0, servant-auth => base>=4.10 && <4.16)
[__2] skipping: servant-auth-0.4.0.0 (has the same characteristics that caused
the previous version to fail: excludes 'base' version 4.9.1.0)
[__2] rejecting: servant-auth-0.3.2.0, servant-auth-0.3.1.0,
servant-auth-0.3.0.1, servant-auth-0.3.0.0, servant-auth-0.2.7.0,
servant-auth-0.2.6.1, servant-auth-0.2.6.0, servant-auth-0.2.1.0,
servant-auth-0.2.0.0, servant-auth-0.1.0.1, servant-auth-0.1.0.0 (constraint
from user target requires ==0.4.1.0)
[__2] fail (backjumping, conflict set: base, servant-auth)
After searching the rest of the dependency tree exhaustively, these were the
goals I've had most trouble fulfilling: base, servant-auth,
cookbook-basic-auth
```

I didn't know how to proceed from there so I moved on to the `stack` instructions.

## stack

The instructions say to do `stack new myproj servant`. I got this error:

```
Downloading lts-18.25 build plan ...RedownloadFailed Request {
host = "raw.githubusercontent.com"
port = 443
secure = True
requestHeaders = []
path = "/fpco/lts-haskell/master//lts-18.25.yaml"
queryString = ""
method = "GET"
proxy = Nothing
rawBody = False
redirectCount = 10
responseTimeout = ResponseTimeoutDefault
requestVersion = HTTP/1.1
}
"/home/mjd/.stack/build-plan/lts-18.25.yaml" (Response {responseStatus = Status {statusCode = 404, statusMessage = "Not Found"}, responseVersion = HTTP/1.1, responseHeaders = [("Connection","keep-alive"),("Content-Length","14"),("Content-Security-Policy","default-src 'none'; style-src 'unsafe-inline'; sandbox"),("Strict-Transport-Security","max-age=31536000"),("X-Content-Type-Options","nosniff"),("X-Frame-Options","deny"),("X-XSS-Protection","1; mode=block"),("Content-Type","text/plain; charset=utf-8"),("X-GitHub-Request-Id","8576:6C91:AEC958:D48EF0:62117EAB"),("Accept-Ranges","bytes"),("Date","Sat, 19 Feb 2022 23:35:07 GMT"),("Via","1.1 varnish"),("X-Served-By","cache-ewr18127-EWR"),("X-Cache","MISS"),("X-Cache-Hits","0"),("X-Timer","S1645313707.372621,VS0,VE68"),("Vary","Authorization,Accept-Encoding,Origin"),("Access-Control-Allow-Origin","*"),("X-Fastly-Request-ID","eac6de468e8caa9cf1b223c412ff01ab7604d49e"),("Expires","Sat, 19 Feb 2022 23:40:07 GMT"),("Source-Age","0")], responseBody = (), responseCookieJar = CJ {expose = []}, responseClose' = ResponseClose})
```

At this point it's not clear how to proceed. I tried cd'ing to the `myproj` directory and running `stack build` as suggested by the next step in the instructions, but the failure was the same.

## nix

The instructions here assume that the user already knows what they are doing. I don't, but I tried anyway. I installed Nix on my system and confirmed that the daemon was running and I could run `nix-shell`. Then I ran `nix-shell nix/shell.nix --arg tutorial true` which seemed to work: it reported downloading dependencies and it gave me a nix-shell prompt. But it's not clear what to do next.

## Additionally

The tutorial docs at https://docs.servant.dev/en/stable/tutorial/install.html say “Copyright 2018”. The `doc/tutorial/install.rst` file was substantively updated in 2019 at commit d4289931ad69f1233c9f75f230f7bb29650df433, so the copyright ought to be at least 2019.

Thanks; please let me know how I can help you resolve this issue.

Start with doc/tutorial/install.rst and compare it with the published installation page. Reproduce the documented cabal-install, stack, and nix steps, then update the instructions so the tutorial has a clear next step after nix-shell and correct the copyright year; done means the documented paths are actionable and the reported failures are addressed.

Written by the indexing model from the issue text.