dev(hansbug): add support for treevalue[potc]

[HansBug]

Description

Add potc support for treevalue

• Update README.md
• Add extra requirements for potc
• Update documentation: https://opendilab.github.io/treevalue/main/tutorials/plugins/index.html#potc-support
• Fix a bug of the size of btv dumped file

Check List

• merge the latest version source branch/repo, and resolve all the conflicts
• pass style check
• pass all the tests

[codecov]

Codecov Report

Merging #26 (a8a3c44) into main (7a627e8) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             main      #26   +/-   ##
=======================================
  Coverage   99.20%   99.20%           
=======================================
  Files          35       35           
  Lines        2013     2013           
=======================================
  Hits         1997     1997           
  Misses         16       16           

Flag	Coverage Δ
unittests	99.20% <ø> (ø)

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