refine docs latest tag to make it ready as default.

[yecol]

Summary

🤖 Generated by Copilot at 1715198

This pull request improves the documentation of GraphScope by updating the website's style and layout, fixing some errors and typos, simplifying some titles and sections, and adding a new document on how to develop custom algorithms. It also removes some unused CSS files and changes the GitHub icon.

[github-actions]

🎊 PR Preview b5c3089 has been successfully built and deployed to https://alibaba-graphscope-build-pr-2788.surge.sh

_{🤖 By surge-preview}

[codecov-commenter]

Codecov Report

Merging #2788 (1715198) into main (09ead30) will not change coverage.
The diff coverage is n/a.

❗ Current head 1715198 differs from pull request most recent head ce17238. Consider uploading reports for the commit ce17238 to get more accurate results

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2788   +/-   ##
=======================================
  Coverage   41.39%   41.39%           
=======================================
  Files          99       99           
  Lines       10381    10381           
=======================================
  Hits         4297     4297           
  Misses       6084     6084           

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