Fix error in exclude section

[mmmbogosian]

Brings INI and TOML examples in line as noted.

[mmmbogosian]

Motivation

The current version of the docs for exclude have the following INI example:

[mypy]
exclude = (?x)(
    ^one\.py$    # files named "one.py"
    | two\.pyi$  # or files ending with "two.pyi"
    | ^three\.   # or files starting with "three."
  )

Shortly after that example, there is a note with the following TOML examples:

[tool.mypy]
exclude = [
  "^file1\\.py$",  # TOML's double-quoted strings require escaping backslashes
  '^file2\.py$',  # but TOML's single-quoted strings do not
]

[tool.mypy]
exclude = '''(?x)(
    ^file1\.py$
    |^file2\.py$,
)'''

The following sentence accompanies the TOML examples:

The [provided] TOML examples are equivalent to the above INI example.

In iterating on #11828 and #11881, those examples diverged such that the quoted sentence was no longer true, but that went undetected (until I went back and read the entry recently).

Correction

make -C docs clean linkcheck does not surface any errors with this page.