docs: fix typos, grammar, and branding consistency across docs and source

[Edge-Explorer]

This commit addresses several documentation quality issues found across the repository — fixing typos, grammar errors, brand name inconsistencies, and adding modern tooling references for new contributors.

Changes

README.md

• Fix duplicate word: "frameworks frameworks" → "frameworks"
• Standardize brand name: "HuggingFace Datasets Hub" → "Hugging Face Datasets Hub"
• Add uv installation section for faster environment setup

CONTRIBUTING.md

• Add uv pip install -e ".[dev]" as an alternative setup command
• Fix grammar: "To do, go" → "To do so, go"
• Fix punctuation: trailing space before period in pre-commit note (again . → again.)
• Standardize brand name: "HuggingFace [code of conduct]" → "Hugging Face [code of conduct]"

docs/source/stream.mdx

• Fix article usage: "a [IterableDataset]" → "an [IterableDataset]" (vowel sound rule)
• Fix code comment: "shuffles the shards order and use" → "uses" (subject-verb agreement)
• Fix phrase: "as soon one of the dataset runs out" → "as soon as one of the datasets runs out"
• Fix pluralization: "every samples in every dataset" → "every sample in every dataset"
• Fix abbreviation punctuation: "i.e the" → "i.e. the"

docs/source/quickstart.mdx

• Standardize brand name: "a HuggingFace [~datasets.Dataset]" → "a Hugging Face [~datasets.Dataset]" (3 occurrences)

docs/README.md

• Standardize copyright notice: "The HuggingFace Team" → "The Hugging Face Team"

notebooks/README.md

• Standardize copyright notice: "The HuggingFace Team" → "The Hugging Face Team"

src/datasets/iterable_dataset.py

• Fix typo in map() docstring: "simulatenous" → "simultaneous"
• Fix typo in filter() docstring: "simulatenous" → "simultaneous"
• Add return type hint to identity_func: (x) → (x: Any) -> Any
• Add return type hint to _rename_columns_fn: missing -> dict return type