[docs] update readme

[Jintao-Huang]

No description provided.

[gemini-code-assist]

Code Review

This pull request updates the documentation in README.md and README_zh.md to mark apex and flash-attn as optional dependencies in the recommended runtime environment tables. The reviewer suggested improving the visual alignment and padding of these table rows to ensure consistency and readability across both the English and Chinese versions of the documentation.

[gemini-code-assist]

The table row for apex is poorly aligned compared to the surrounding rows. Standardizing the column widths to match the table header and separator improves the readability of the document in raw text format.

Suggested change

	| apex | | 0.1 | Optional |
	| apex | | 0.1 | Optional |

[gemini-code-assist]

The table row for flash-attn has inconsistent padding. Aligning the columns with the rest of the table makes the documentation more professional and easier to maintain.

Suggested change

	| flash-attn | | 2.8.3/3.0.0b1 | Optional |
	| flash-attn | | 2.8.3/3.0.0b1 | Optional |

[gemini-code-assist]

The alignment for the apex row is inconsistent with the rest of the table. Standardizing the column widths improves the visual structure and maintainability of the document.

Suggested change

	| apex | | 0.1 | 可选 |
	| apex | | 0.1 | 可选 |

[gemini-code-assist]

The flash-attn row is misaligned and contains excessive padding in the 'Notes' column. Suggesting a cleaner, standardized format.

Suggested change

	| flash-attn | | 2.8.3/3.0.0b1 | 可选 |
	| flash-attn | | 2.8.3/3.0.0b1 | 可选 |