Update docs in BatchExportProcessorOptions.cs

[marcinjahn]

Fixes #
Minor summary leftover

Changes

• fix BatchExportProcessorOptions.MaxExportBatchSize summary

Merge requirement checklist

• CONTRIBUTING guidelines followed (license requirements, nullable enabled, static analysis, etc.)
• Unit tests added/updated
• Appropriate CHANGELOG.md files updated for non-trivial changes
• Changes in public API reviewed (if applicable)

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 86.30%. Comparing base (0c53d9f) to head (10c3847).
Report is 3 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #6177   +/-   ##
=======================================
  Coverage   86.30%   86.30%           
=======================================
  Files         257      257           
  Lines       11499    11499           
=======================================
  Hits         9924     9924           
  Misses       1575     1575           

Files with missing lines	Coverage Δ
src/OpenTelemetry/BatchExportProcessorOptions.cs	100.00% <ø> (ø)

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