fix: correct invalid Liquid syntax in image.html include

[praaatap]

Description

This Pull Request resolves a common syntax error in the [_includes/image.html] file, where Liquid output tags were mistakenly placed inside logic tags. It also introduces minor security hardening to external links.

Changes Made

• Corrected Liquid Syntax: Stripped the nested {{ }} tags inside {% if %} tags. In Liquid syntax, logic tags are evaluated directly from the context, and placing output tags inside them is actually incorrect syntax that may cause build warnings or unexpected rendering issues.
• Security Hardening: Added rel="noopener noreferrer" to external links with target="_blank". This is a current best practice for web security to prevent tab-nabbing and improve user privacy when leaving the documentation site.

How to test

1. Build the Jekyll site locally: bundle exec jekyll serve
2. Open any page with the [image.html]include (such as the 404 page).
3. Verify that the image URLs are still properly rendered.

[hanzalahwaheed]

@MakisH LGTM!

[hanzalahwaheed]

@praaatap solid PR. please rebase and update the branch for merging.

[MakisH]

Thanks!