docs: improve hybrid cmd section

[AstreaTSS]

Pull Request Type

• Feature addition
• Bugfix
• Documentation update
• Code refactor
• Tests improvement
• CI/CD pipeline enhancement
• Other: [Replace with a description]

Description

This PR slightly improves the hybrid command section in the slash command section. This should hopefully feature clearer wording, a better header (that works way better for searching), and a bit more information.

Changes

• Change title from "Prefixed/Text Commands" to "Hybrid Commands", as the former title makes little sense in context.
• Otherwise, see diff.

Related Issues

Test Scenarios

Python Compatibility

• I've ensured my code works on Python 3.10.x
• I've ensured my code works on Python 3.11.x

Checklist

• I've run the pre-commit code linter over all edited files
• I've tested my changes on supported Python versions
• I've added tests for my code, if applicable
• I've updated / added documentation, where applicable