Some docs optimization

[zhaojiandong]

Some docs optimization

[gianm]

The [text](url) syntax should work fine and is standard for Markdown. Was something not working with it? (I notice one of the links had a link break between [SegmentMetadataQuery] and (../querying/segmentmetadataquery.html), that one probably needed to be connected.

[zhaojiandong]

Maybe github hasn't supported markdown="1" :

<div markdown="1">
    #Heading 1
</div>

It's not work @gianm

[gianm]

Oh, I guess inside HTML, markdown isn't respected? I didn't realize that.

[zhaojiandong]

I guess so~

[jon-wei]

Hm, I don't think this encoding is working: https://github.com/apache/incubator-druid/blob/1d100a54f70c00729f0b33d32ae6a2a042b48cb7/docs/content/querying/sql.md

[gianm]

After playing around a bit I found something that works:

|<code>x &#124;&#124; y</code>|Concat strings x and y.|

[zhaojiandong]

It works! 👍

[zhaojiandong]

I found it works in https://github.com/zhaojiandong/druid/blob/master/docs/content/querying/sql.md
not work in https://github.com/apache/incubator-druid/blob/57d95fe194df9af00687203950fa86a2fe9e025d/docs/content/querying/sql.md