docs: update Textract docs

[ahmadelmalah]

I am modifying two things:

1. "This sample demonstrates" with "The following samples demonstrate" as we're talking about at least 4 samples
2. Bringing the sentence to after talking about the definition of textract to keep the document organized (textract definition then samples)

[vercel]

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Name	Status	Preview	Comments	Updated (UTC)
langchain	✅ Ready (Inspect)	Visit Preview	💬 Add feedback	Jul 14, 2025 3:36pm

[codspeed-hq]

CodSpeed WallTime Performance Report

Merging #31992 will improve performances by 17.9%

_{Comparing ahmadelmalah:textract (2c0e160) with master (6dcca35)}

⚠️ Unknown Walltime execution environment detected

Using the Walltime instrument on standard Hosted Runners will lead to inconsistent data.

For the most accurate results, we recommend using CodSpeed Macro Runners: bare-metal machines fine-tuned for performance measurement consistency.

Summary

⚡ 11 improvements
✅ 2 untouched benchmarks

Benchmarks breakdown

	Benchmark	BASE	HEAD	Change
⚡	test_import_time[BaseChatModel]	569.1 ms	502.7 ms	+13.21%
⚡	test_import_time[CallbackManager]	471.7 ms	416 ms	+13.37%
⚡	test_import_time[ChatPromptTemplate]	453.3 ms	401.7 ms	+12.85%
⚡	test_import_time[Document]	206.2 ms	185.1 ms	+11.45%
⚡	test_import_time[InMemoryRateLimiter]	182.8 ms	161.8 ms	+12.98%
⚡	test_import_time[InMemoryVectorStore]	273 ms	239.1 ms	+14.19%
⚡	test_import_time[LangChainTracer]	478.8 ms	406.1 ms	+17.9%
⚡	test_import_time[PydanticOutputParser]	425.4 ms	362.4 ms	+17.39%
⚡	test_import_time[RunnableLambda]	265.8 ms	231 ms	+15.08%
⚡	test_import_time[Runnable]	261 ms	226.7 ms	+15.16%
⚡	test_import_time[tool]	532.8 ms	465.8 ms	+14.39%

[codspeed-hq]

CodSpeed Instrumentation Performance Report

Merging #31992 will not alter performance

_{Comparing ahmadelmalah:textract (2c0e160) with master (6dcca35)}

Summary

✅ 14 untouched benchmarks