Fix code examples and improve documentation in language reference

[jeroenlm]

Description

• Fix code example in composite-types part
• Remove false statement in composite-types part
• Remove typo in the functions part
• Fix code example in restricted-types part

PS: this is my very first PR. Feel free to give any feedback!

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For contributor use:

• Targeted PR against master branch
• Linked to Github issue with discussion and accepted design OR link to spec that describes this work
• Code follows the standards mentioned here
• Updated relevant documentation
• Re-reviewed Files changed in the Github PR explorer
• Added appropriate labels

[turbolent]

@jeroenlm Thank you for the fixes!

Looks good, I just have one question

[turbolent]

Was this line removed on purpose? If it doesn't make sense, I think we need to extend it / improve the wording

[jeroenlm]

I removed this line on purpose indeed. When you scroll up a little bit on that page (composite-types), there is written: "Nesting of resources is only allowed within other resource types, or in data structures like arrays and dictionaries, but not in structures, as that would allow resources to be copied." Since resources are composite types, this means that composite types can be nested in some cases. That's why I removed that line. Does it make sense? Or maybe am I misunderstanding the writer of that sentence?

[turbolent]

Yeah, I guess we can remove that sentence 👍

[jeroenlm]

Great! Very happy with my first contribution :)