docs: improve README header with badges and fix ip install typo

[ko3n1g]

Claude summary

Summary

• Adds a centered <div align="center"> header to README.md matching the style of other NeMo repos (Megatron-Bridge), with four badges (Codecov, CI/CD, Python 3.10+, GitHub Stars) and navigation quick-links (Documentation · Examples · Contributing · FAQs)
• Removes the redundant embedded table of contents
• Minor cleanup: drops noisy inline comment # Local executor, removes trailing periods from tutorial links, promotes #### Hello world to ### Hello world for consistent heading hierarchy, renames "Contribute to NeMo Run" → "Contributing"
• Fixes a ip install → pip install typo in docs/index.md

Example header

NeMo Run

Documentation | Examples | Contributing | FAQs

Test plan

• README renders correctly on GitHub (badges resolve, nav links work)
• docs/index.md install command correct