Remove 'why not arrow' section from docs

[jadchaar]

Pull Request Check List

• Added tests for changed code.
• Updated documentation for changed code.

The "Why not Arrow?" section of the documentation is no longer relevant since all of these issues have been resolved in Arrow since version 0.17.0 (released last year):

env ❯ python3
Python 3.9.5 (default, May  4 2021, 03:36:27)
[Clang 12.0.0 (clang-1200.0.32.29)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> import arrow
>>> import pendulum
>>> arrow.__version__
'1.1.0'
>>> pendulum.__version__
'2.1.2'
>>> arrow.get('2016-1-17')
2016-01-17T00:00:00+00:00
>>> pendulum.parse('2016-1-17')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/Users/jadchaar/Downloads/test-arrow/env/lib/python3.9/site-packages/pendulum/parser.py", line 29, in parse
    return _parse(text, **options)
  File "/Users/jadchaar/Downloads/test-arrow/env/lib/python3.9/site-packages/pendulum/parser.py", line 45, in _parse
    parsed = base_parse(text, **options)
  File "/Users/jadchaar/Downloads/test-arrow/env/lib/python3.9/site-packages/pendulum/parsing/__init__.py", line 74, in parse
    return _normalize(_parse(text, **_options), **_options)
  File "/Users/jadchaar/Downloads/test-arrow/env/lib/python3.9/site-packages/pendulum/parsing/__init__.py", line 128, in _parse
    raise ParserError("Unable to parse string [{}]".format(text))
pendulum.parsing.exceptions.ParserError: Unable to parse string [2016-1-17]
>>> arrow.get('20160413')
2016-04-13T00:00:00+00:00
>>> pendulum.parse('20160413')
2016-04-13T00:00:00+00:00
>>> arrow.get('2016-W07-5')
2016-02-19T00:00:00+00:00
>>> pendulum.parse('2016-W07-5')
2016-02-19T00:00:00+00:00
>>> just_before = arrow.Arrow(2013, 3, 31, 1, 59, 59, 999999, 'Europe/Paris')
>>> just_before
<Arrow [2013-03-31T01:59:59.999999+01:00]>
>>> just_after = just_before.shift(microseconds=1)
>>> just_after
<Arrow [2013-03-31T03:00:00+02:00]>
>>> (just_after.to('utc') - just_before.to('utc')).total_seconds()
1e-06
>>> just_before = pendulum.datetime(2013, 3, 31, 1, 59, 59, 999999, 'Europe/Paris')
>>> just_before
DateTime(2013, 3, 31, 1, 59, 59, 999999, tzinfo=Timezone('Europe/Paris'))
>>> just_after = just_before.add(microseconds=1)
>>> just_after
DateTime(2013, 3, 31, 3, 0, 0, tzinfo=Timezone('Europe/Paris'))
>>> (just_after.in_timezone('utc') - just_before.in_timezone('utc')).total_seconds()
1e-06

Since all of these issues are now resolved, I think it is fair to remove this section from the documentation :). Disclaimer: I am one of the maintainers of Arrow.

Thanks in advance!