Add comments for html5ever/examples

[organic1337]

My first PR here :)

I decided I wanted to contribute to this cool project, and when I started learning about it, I headed over to the examples directory, and it was quite hard for me to understand what I was reading because it lacked some comments.

Someone already opened an issue about it.

Changes

• Add comments to the main function in each example with a short description of what the code does.
• Added comments for structs and traits implemented in the examples.
• Move the main function in arena.rs example to the end of the file (to match the other examples)

[mrobinson]

I could see us adding comments on particularly tricky parts of the code and maybe succinct descriptions of what the examples do, but I don't think we need comments of the type:

// Create a new arena
let arena = typed_arena::Arena::new();

which simply repeat what the code itself is saying. In general, clearer code and better variables names are preferred to comments for me.

Quick question though: Were these comments generated with a large language model like ChatGPT? I don't think we want AI generated code or comments at the moment. Thanks for understanding.

[organic1337]

Hi Martin thx for the comment.

I've removed some comments which just repeat simple code (like the arena example)

There's no doubt that good naming and self-explanatory code are much better than comments. Though in the case of code example, comments can make the newbie developers' life easier.

I wanted to step into this project in order to contribute it in some way, and the examples/ folder was the first place I visited, and tbh, I did not understand much just from reading it... I had to dig deeper in the library to fully understand what's going on there and understand the terminology.

And no, non of these comments were generated by any kind of LLM, as I mentioned before I'm interested to help develop this project so I wanted to actually learn how it works.

[mrobinson]

Thanks for the clarification and the contribution.

[rillian]

Seems like a useful improvement to me.

[rillian]

@organic1337 this needs rebasing past #520 if you're still interested in working on it.