Add topMargin property in window.$docsify for better layout

[alanvww]

Hi folks, for the current docsify page, there is an issue that when the user uses the section links in the sidebar, the scroll offset is not ideal.

After some research, there is a option called "topMargin" in docsify can solve this problem.

in index.html

<script>
window.$docsify = {
	......
	topMargin: 30,
.........
</script>

after this option applied

Related #68

[QuinnHe]

Thanks, @alanvww! Love it! Feel free to create a PR and we will merge your changes to the main. cc @MOQN

[alanvww]

Thanks, @alanvww! Love it! Feel free to create a PR and we will merge your changes to the main. cc @MOQN

Done! Sorry for the reformatting of the files :( I Please use the "ignore whitespace" when reviewing the code.
#71