i18n: bring README.hi.md up to date with v1.0

[Cryptoteep]

🌐 Bring README.hi.md up to date with v1.0

The Hindi translation (#7, thanks @dev-khimesh!) was made from the README as of v0.2. The English README has since grown with the v0.3–v1.0 features. Missing from the Hindi version:

• CLI examples: color harmonies (v0.3), ∆E2000 / ∆E76 difference (v0.3, v0.5), mix/rotate/complement/lighten + palette utilities (v0.4), palette import & seed inference (v0.6), WCAG-conformant pairs & palette audit (v0.7), WCAG 2.2 non-text contrast (v0.8), CSS display-p3 export (v0.9), unified accessibility report (v1.0)
• Features list additions for the same releases
• Roadmap section (several items shipped since)
• API section: newer helpers

Guidelines are the same as #5: translate the prose, keep code blocks and API names in English. Partial PRs are welcome — even one section helps.