[Docs] Update metafile and Readme

[mzr1996]

Motivation

According to the new metafile standard to update our metafiles.
According to benchmark regression results to update some accuracy result in our readme. Refers to #283 and #288

Modification

1. Add the paper title, code link, and code version information.
2. Add third-party checkpoints source URL and code information.
3. Add Readme and metafile of Transformer-in-Transformer.
4. Update some outdated accuracy information in metafiles.
5. Upload new checkpoints of ResNet to confirm reproducibility.

Checklist

Before PR:

• Pre-commit or other linting tools are used to fix the potential lint issues.
• Bug fixes are fully covered by unit tests, the case that causes the bug should be added in the unit tests.
• The modification is covered by complete unit tests. If not, please add more unit test to ensure the correctness.
• The documentation has been modified accordingly, like docstring or example tutorials.

After PR:

• If the modification has potential influence on downstream or other related projects, this PR should be tested with those projects, like MMDet or MMSeg.
• CLA has been signed and all committers have signed the CLA in this PR.

[codecov]

Codecov Report

Merging #435 (6f5ffb5) into master (a8f4f82) will increase coverage by 0.01%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master     #435      +/-   ##
==========================================
+ Coverage   77.27%   77.29%   +0.01%     
==========================================
  Files         100      100              
  Lines        5356     5356              
  Branches      883      883              
==========================================
+ Hits         4139     4140       +1     
  Misses       1098     1098              
+ Partials      119      118       -1     

Flag	Coverage Δ
unittests	77.29% <ø> (+0.01%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
mmcls/models/backbones/swin_transformer.py	90.07% <0.00%> (+0.70%)	⬆️

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[Ezra-Yu]

LGTM.

[zhouzaida]

URI -> URL?