Update README for the recently released features

[haeter525]

Description
Close #366.
This PR aims to do the following improvements on README.

1 - Clean up outdated information

• Change the link of social media to Quark's Twitter account. (ac44d10)
• Fix the wrong commands in the Detail Report section. (4b648e3)
• Add an introduction for Detection Rules Viewer. (2339018)

2 - Simplify the content

• Move the screenshots into the collapsible sections. (54cc4e1)
• Simplify the description of getting the latest rules. (f29a322)

3 - Adjusting the layout

• Add an overview of all the features. (24e2838)
• Rearrange the introduction of each report according to the above overview. (dba524e)
• Move the introductions of the features downward. (5c2a664)

Test Plans
All commands in README have been tested.

[codecov-commenter]

Codecov Report

Merging #367 (bef1fb2) into master (be21897) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #367   +/-   ##
=======================================
  Coverage   74.21%   74.21%           
=======================================
  Files          52       52           
  Lines        3933     3933           
=======================================
  Hits         2919     2919           
  Misses       1014     1014           

Flag	Coverage Δ
unittests	74.21% <ø> (ø)

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