Doctest failure

[wRAR]

Merging #5256 introduced a doctest failure in docs/intro/tutorial.rst:

Expected:
    Traceback (most recent call last):
    File "<console>", line 1, in <module>
    ...
    IndexError: list index out of range
Got:
    Traceback (most recent call last):
      File "/opt/hostedtoolcache/Python/3.7.12/x64/lib/python3.7/doctest.py", line 1337, in __run
        compileflags, 1), test.globs)
      File "<doctest None[0]>", line 1, in <module>
      File "/home/runner/work/scrapy/scrapy/.tox/py/lib/python3.7/site-packages/parsel/selector.py", line 70, in __getitem__
        o = super(SelectorList, self).__getitem__(pos)
    IndexError: list index out of range

[Gallaecio]

I think we just need to remove the File "<console>", line 1, in <module> line from the documentation, as it does not (cannot) match the actual output.

[jmherbst]

I'm happy to make this change :)