fix highlightjs bug with code block
fix highlightjs bug with code block

We should distinguish <code> and <pre><code>.

Signed-off-by: Le Tan <7d16f0b5dfe3192737120adbafd0f704bf1b8474@gmail.com>

tamlok/vnote,tamlok/vnote,tamlok/vnote,tamlok/vnote,tamlok/vnote