docs/library/socket: Document socket.write(buf, offset, max_len). - #19739

Summary

I found some un(der)documented overloads of socket.socket.write() while improving and testing the stubs.
These should be added to the documentation, especially as they as MicroPython specific extensions.

Testing

Both undocumented forms are already part of the test suite:

• tests\basics\io_write_ext.py

buf.write(b"foobar", 1, 3)
print(buf.getvalue())

buf.write(b"foobar", 1, 100)
print(buf.getvalue())

buf.write(b"foobar", 100, 100)
print(buf.getvalue())

Generative AI

I used generative AI tools when creating this PR, but a human has checked the
code and is responsible for the code and the description above.