Support for Hiden anchor

[seaspeak]

Is your feature request related to a problem? Please describe.
Hiden anchor (<a id=anchor-name></a>) is a trick to let you jump to any position in the document.

Describe the solution you'd like
Title Anchor is now supported, but not hiden anchor.
The usage is the same as title anchor.
[name](#anchor-name)

Describe alternatives you've considered

Additional context
<a id=''></a>, <a name=''></a> theoretically should do. But "name" could be deprecated in the future.