docs: fix broken link

[futreall]

Description of changes:

• Fixed the broken link to the celestia-node installation documentation (404 error).
• Replaced it with the correct, working link: Install celestia-node | Celestia Docs, which contains detailed installation and configuration instructions for celestia-node.

Thanks for your hard work! I hope this helps you !

[futreall]

@Wondertan Hey ! Thanks for your work , check this PR

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 45.40%. Comparing base (2469e7a) to head (c83f59a).
Report is 416 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4011      +/-   ##
==========================================
+ Coverage   44.83%   45.40%   +0.56%     
==========================================
  Files         265      309      +44     
  Lines       14620    22279    +7659     
==========================================
+ Hits         6555    10115    +3560     
- Misses       7313    11089    +3776     
- Partials      752     1075     +323     

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