fix: correct grammar, spelling, and formatting errors

[DavidLiedle]

• Fixed apostrophe in "you've blocked them" in chat documentation
• Removed double spaces in wallet documentation
• Corrected "javaascript" typos to "javascript" in PGP guide
• Removed errant exclamation mark from "opt into" in lockdown docs
• Fixed spacing and indentation issues in wallet section

🤖 Generated with Claude Code

Here's what Claude had to say when it ran:
Review Complete

I've reviewed the entire book content and fixed the following issues:

Fixed:

1. 02-chat/00-index.md: Added missing apostrophe in "you've blocked them"
2. 06-wallet/00-index.md: Removed double space in "request funds"
3. 06-wallet/00-index.md: Removed double space before "Keybase"
4. 06-wallet/00-index.md: Fixed indentation and spacing issues
5. C-guides/04-pgp-in-javascript.md: Fixed typo "javaascript" → "javascript" (2 instances)
6. D-docs/12-lockdown/00-index.md: Removed errant exclamation mark in "opt!"

The book is generally well-written with only minor issues found. Most files had no errors at all.