v0.7.0: directory tree search, sidebars, anchors, and scroll-spy

From now on, Antmarky goes through all the child folders inside the documentation directory to search for Markdown files.

This release also brings important visual updates:

• sidebars are now remain fixed when scrolling content
• you can now get a link to the specific heading by clicking the anchor (hashtag) next to it
• table of contents now highlights the heading you are currently reading

Full changelog