Update opensearch-api-spec maintainers (#1162)

* Add Sean Chittenden as maintainer

Signed-off-by: Xi Lu <fridalu66@gmail.com>

* Update Sean maintainer affiliation and codeowners

Signed-off-by: Xi Lu <fridalu66@gmail.com>

* Update MAINTAINERS.md

Signed-off-by: Sean Chittenden <sean.chittenden@crowdstrike.com>

---------

Signed-off-by: Xi Lu <fridalu66@gmail.com>
Signed-off-by: Sean Chittenden <sean.chittenden@crowdstrike.com>
Co-authored-by: Sean Chittenden <sean.chittenden@crowdstrike.com>

Author: lucy66hw

.github/CODEOWNERS

@@ -1 +1 @@
-*   @harshavamsi @sachetalva @Xtansia @VachaShah @Tokesh @aabeshov @karenyrx @lucy66hw
+*   @harshavamsi @sachetalva @Xtansia @VachaShah @Tokesh @aabeshov @karenyrx @lucy66hw @sean-

MAINTAINERS.md

@@ -13,6 +13,7 @@ This document contains a list of maintainers in this repo. See [opensearch-proje
 | Harsha Vamsi Kalluri | [harshavamsi](https://github.com/harshavamsi) | Amazon      |
 | Karen Xu             | [karenyrx](https://github.com/karenyrx)       | Uber        |
 | Sachet Alva          | [sachetalva](https://github.com/sachetalva)   | Amazon      |
+| Sean Chittenden      | [sean-](https://github.com/sean-)             | CrowdStrike |
 | Thomas Farr          | [Xtansia](https://github.com/Xtansia)         | Independent |
 | Torekeldi Niyazbek   | [Tokesh](https://github.com/Tokesh)           |             |
 | Vacha Shah           | [VachaShah](https://github.com/VachaShah)     | Amazon      |
@@ -26,4 +27,4 @@ This document contains a list of maintainers in this repo. See [opensearch-proje
 | Abhi Kalra         | [abhivka7](https://github.com/abhivka7) | Amazon      |
 | Daniel Doubrovkine | [dblock](https://github.com/dblock)     | Independent |
 | Pranav Garg        | [pgtgrly](https://github.com/pgtgrly)   | Amazon      |
-| Theo Truong        | [nhtruong](https://github.com/nhtruong)       | Independent |
+| Theo Truong        | [nhtruong](https://github.com/nhtruong) | Independent |