docs: Fix preposition phrasing and missing comma in client quickstart

[LaRoyBot]

Fixes preposition phrasing ("introduction in how" -> "introduction to how") and adds a missing comma in client quickstart documentation.

[codspeed-hq]

Merging this PR will not alter performance

✅ 83 untouched benchmarks
⏩ 83 skipped benchmarks¹

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_{Comparing LaRoyBot:docs-fix-client-quickstart-phrasing (ade06dd) with master (8e814f5)²}

Footnotes

1. 83 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩

2. No successful run was found on master (62f0f90) during the generation of this report, so 8e814f5 was used instead as the comparison base. There might be some changes unrelated to this pull request in this report. ↩