til add and note entry metadata

[schneedotdev]

Changes

• Replaced that command with add
• Removed --message flag
• Added optional --tags flag that accepts command-separated values (no spaces) to be added to the metadata of a note entry
• Generate metadata when a new entry is created using generate_meta
• update_meta is used when new tags are passed to the program. They are appending to the tags section of a note's metadata:

---
title: "example"
tags: ["tag1", "tag2"]
---

• Update README.md with command information
• Add detailed comments to new functions with function usage.