docs: Add API key acquisition instructions and fix username template …

[ashvin2005]

This PR fixes two documentation issues in the attribute templates:

1. API Key Instructions: Added clear guidance on how to acquire API keys by mentioning that users can find them in their account settings under "API Tokens" or "API Keys" section.

2. Username Template Error: Removed the erroneous {{ undesc }} placeholder that was displaying as raw text in the username parameter description.

Changes Made

• Updated snippets/attributes/apikey.md to include API key acquisition instructions
• Fixed snippets/attributes/username.md by removing the {{ undesc }} template variable

Related Issues

Fixes documentation clarity issues for all modules using these attribute templates.

Checktoberfest

This PR is submitted as part of Hacktoberfest 2025 🎃

[FelicianoTech]

@ashvin2005 Was this PR made with AI?

[ashvin2005]

@FelicianoTech
No, the PR wasn’t generated by AI , I wrote and reviewed the changes myself.....
I only used AI tools to mprove clarity, but all edits and context were done manually.
Thanks for checking, I completely understand the need to verify authenticity....