Docs: Fix broken TOC links and update dead external references

[Konki29]

Reference issue

N/A (Found while reading documentation)

What does this implement/fix?

This PR fixes broken links in the README.md:

1. Table of Contents anchors: Fixed internal links that were broken due to parenthesis and special characters in the section headers (e.g., Documentation).
2. External References: Updated dead links (404) for "Reeds-Shepp Curves" and "SLAM simulations by Tim Bailey" to their new active URLs (LaValle's official site and OpenSLAM).

Additional information

I have manually verified that the new external URLs are active and point to the correct resources.

CheckList

• All CIs are green? (You can check it after submitting)
• Did you add documents for your new example?
• Did you add an unittest for your new example or defect fix?