docs: add maintainers document (#2088)

* add maintainers

Signed-off-by: yisaer <disxiaofei@163.com>

* chore: add more maintainers

Signed-off-by: Jiyong Huang <huangjy@emqx.io>

---------

Signed-off-by: yisaer <disxiaofei@163.com>
Signed-off-by: Jiyong Huang <huangjy@emqx.io>
Co-authored-by: Jiyong Huang <huangjy@emqx.io>

MAINTAINERS.md

@@ -0,0 +1,24 @@
+Maintainers
+===========
+
+List all maintainers in alphabetical order.
+
+**Active Maintainers**
+
+| Name          | GitHub ID                                   | Email                   |
+|---------------|---------------------------------------------|-------------------------|
+| Fahua Jin     | [jinfahua](https://github.com/jinfahua)     | <rocky@emqx.io>         |
+| JianXiang Ran | [superrxan](https://github.com/superrxan)   | <rxan_embedded@163.com> |
+| Jiyong Huang  | [ngjaying](https://github.com/ngjaying)     | <ngjaying@gmail.com>    |
+| Rory Zhang    | [Rory](https://github.com/Rory-Z)           | <rory-z@outlook.com>    |
+| Rui Gan       | [Regina](https://github.com/Rui-Gan)        | <1171530954@qq.com>     |
+| Song Gao      | [yisaer](https://github.com/yisaer)         | <disxiaofei@163.com>    |
+| Yongxing Ma   | [yongxingMa](https://github.com/yongxingMa) | <726518972@qq.com>      |
+
+**Documentation Maintainers**
+
+| Name      | GitHub ID                                     | email                  |
+|-----------|-----------------------------------------------|------------------------|
+| Ming Zhao | [Ming](https://github.com/Swilder-M)          | <poxiaobbs@gmail.com>  |
+| Na Pan    | [LenaLenaPan](https://github.com/LenaLenaPan) | <hilena.pan@gmail.com> |
+