RFR: Add jextract guide [v5]

[Maurizio Cimadamore]

On Fri, 12 Apr 2024 12:49:39 GMT, Nir Lisker <nlisker at openjdk.org> wrote:

>> Jorn Vernee has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Phrasing
>>   
>>   Co-authored-by: Maurizio Cimadamore <54672762+mcimadamore at users.noreply.github.com>
>
> doc/GUIDE.md line 84:
> 
>> 82: 
>> 83: The `<libspec>` argument of the `--library` option can either be a library name, such as,
>> 84: `mylib` which will, be mapped to a platform specific name using [`System::mapLibraryName`](https://docs.oracle.com/en/java/javase/22/docs/api/java.base/java/lang/System.html#mapLibraryName(java.lang.String)), or a path to a library file (either relative or
> 
> Comma after `mylib` instead of after `will`.

I'd also drop the comma after `such as`

> doc/GUIDE.md line 134:
> 
>> 132: builtin C types.
>> 133: 
>> 134: The latter import statement imports all the other classes the jextract generates, which
> 
> "that jextract generates"

or, `generated by jextract`

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PR Review Comment: https://git.openjdk.org/jextract/pull/231#discussion_r1563202919
PR Review Comment: https://git.openjdk.org/jextract/pull/231#discussion_r1563203920