update logo. remove image.
Revert "update logo. remove image."

This reverts commit c3e2714fdbf708e81048fe58b3ffdf86ab1b346d.
Revert "Update README."

This reverts commit 33f0a2b7ea70a9a036a2626e0d431aa1eeafbfef.
Revert "No Toc message if empty."

This reverts commit 6130fe1621bf46d4944643cc40570cd4417ad46d.