Fix minor mistakes

[jamessspanggg]

Fixes #81

• remove unnecessary toc in usage.md
• fix logos in questions to use {{ icon_Q_A }} and {{ icon_Q }} respectively
• refactor all Github -> GitHub
• add missing review section in integration: Link to fixed section in preview
• removes unused Java section in LOs and TOC, since replaced by C++ to Java
• match the printable version with normal version by moving Principles from Supplementary section to under its own Principles section. Added C++ to Java content to the printable version under Supplementary
• fix duplicate pageNav stash component in Git and GitHub: Link to fixed section in preview

[jamessspanggg]

@damithc ready for review.