Related Issue

Fix: #503

Description

As per i said in issue i have created new secion of thymeleaf in JAVA
and added 4 files

1. introduction to thymeleaf
2. synhtaxes in thymeleaf
3. iteration and conditional evalution in thymeleaf
4. category.json

also given best content and used only official documentation and added best parts of that

Type of PR

• Feature enhancement
• Documentation update

Screenshots / Videos (if applicable)

[Attach any relevant screenshots or videos demonstrating the changes]

Checklist

• I have performed a self-review of my code.
• I have read and followed the Contribution Guidelines.
• I have tested the changes thoroughly before submitting this pull request.
• I have provided relevant issue numbers, screenshots, and videos after making the changes.
• I have commented my code, particularly in hard-to-understand areas.

Additional Context

please look over my work in file changes
and please if you think that this is deserving more than level2 then please upgrade it
i am not doing repetitive task or just running one code or giving one code solution
gone thorugh official docs and getting this, at the end it's upto you
thank you

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