Add demo.html to demonstrate SBGNViz.js usage #209

[rajanarahul93]

This PR adds a demo.html file to demonstrate how to use SBGNViz.js in an HTML file. The example includes:

• Loading Cytoscape.js and SBGNViz.js.
• Initializing SBGNViz and rendering an SBGN-ML file.
• A simple container for visualization.
  How to cite the sbgnviz.js into the <script> lable of html? #209

[hasanbalci]

@rajanarahul93 Are you sure that your demo.html file is working?

[rajanarahul93]

@hasanbalci Yes, I have tested the demo.html file, and it is working correctly. The SBGN-ML file loads as expected. Let me know if you have any suggestions for improvements

[hasanbalci]

But you are referring to non-existing files such as dist/sbgnviz.min.js and dist/sbgnviz.css. Sbgnviz doesn't have a dist folder. It also doesn't have any function named loadSbgn.

[rajanarahul93]

Thank you for pointing that out, @hasanbalci. I see the mistake regarding the dist/ folder and the loadSbgn function. Could you clarify the correct way to reference SBGNViz.js in the script and how to load an SBGN-ML file? I’ll make the necessary corrections accordingly.