fix github readme page jump title position && add kotlin.org for support.

[alan636]

above

[hikerpig]

Thanks for your work, I will have some tests and manage the release afterwards.

[hikerpig]

The github readme page offset fix is ok.

But I'm a little comfused about the kotlinlang.org change, could you provide an example url for me to test ? For I find it already has toc in its docs page, and this change seems to have non effect on it.