docs: align the naturaldelta example with minute rounding

[Likio3000]

The README still shows naturaldelta(timedelta(seconds=1001)) returning 16 minutes, although #272 changed naturaldelta to round to the nearest unit. Update the expected output to 17 minutes so the example matches the current implementation and documented behavior.

Changes proposed in this pull request:

• Correct this one README output line; no implementation changes.

Validation: statically checked the minute branch (round(delta.seconds / 60)), the rounding docstring, the existing 1m29s/1m30s/1m59s test cases, and the changes in #272. Independently checked the arithmetic for 1001 seconds. I did not run Humanize, its test suite, linting, or the documentation build.

Prepared with assistance from OpenAI Codex.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 99.69%. Comparing base (392aef7) to head (bf5a961).

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #410   +/-   ##
=======================================
  Coverage   99.69%   99.69%           
=======================================
  Files          12       12           
  Lines         996      996           
=======================================
  Hits          993      993           
  Misses          3        3           

Flag	Coverage Δ
macos-latest	97.59% <ø> (ø)
ubuntu-latest	97.59% <ø> (ø)
windows-latest	93.27% <ø> (ø)

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