[CELEBORN-1870] Fix typos in in 'Developer' documents

[bgeng777]

What changes were proposed in this pull request?

Fix typo in 'Developer' documents.

Why are the changes needed?

Improve the accurary of the doc.

Does this PR introduce any user-facing change?

No.

How was this patch tested?

Only doc changed. No test.

[FMX]

LGTM. Thanks. Merged into main(v0.6.0).

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 32.70%. Comparing base (fdf1883) to head (95265ab).
Report is 18 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3108      +/-   ##
==========================================
+ Coverage   32.62%   32.70%   +0.08%     
==========================================
  Files         336      337       +1     
  Lines       20083    20155      +72     
  Branches     1798     1804       +6     
==========================================
+ Hits         6551     6590      +39     
- Misses      13165    13200      +35     
+ Partials      367      365       -2     

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