[Update] Cleanup and Indexes

Hi Everyone,

I did a bit of cleaning today on the Guide. Nothing major:

Version 1.2.1 - 24 January 2024

• [24-Jan] - Added Function/Method Index + API Index
• [24-Jan] - Completed the TODO comments
• [24-Jan] - Removed the //New// and //Updated// signs
• [24-Jan] - Fixed typos, broken links
• [24-Jan] - Reformatted the Macro Index