Update 1min demo data in CSV format

[arisliang]

Description

Motivation and Context

How Has This Been Tested?

• Pass the test by running: pytest qlib/tests/test_all_pipeline.py under upper directory of qlib.
• If you are adding a new feature, test on your own test scripts.

Screenshots of Test Results (if appropriate):

1. Pipeline test:
2. Your own tests:

Types of changes

• Fix bugs
• Add new feature
• Update documentation

[you-n-g]

@arisliang Thanks for your PR very much
Could you give a more detailed description of how to get the demo csv data.

For example

Besides downloading the prepared demo data, users could download demo data directly from the Collector.
here are some example

for daily data
....

for 1min data
....

[arisliang]

Updated the document, is that change what you mean?

[you-n-g]

@arisliang
It looks great! Thanks so much!