docs: Example mismatch when changing language JS/TS (#61833)
### What?
Resolves issue #61695
### Why?
The `Building Your Application -> Data Fetching -> Server Actions and
Mutations` section in the Next.js documentation has a few mismatches
with respect to JS and TS codes.
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Co-authored-by: battuAshita <battua@iitbhilai.ac.in>
Co-authored-by: Sam Ko <sam@vercel.com>
