Add @sachinpkale as an OpenSearch maintainer (opensearch-project#8019)

I have nominated and maintainers have agreed to invite Sachin Kale
(@sachinpkale) to be a co-maintainer. Sachin has kindly accepted.

Sachin has led the design and implementation of the remote backed
storage feature in OpenSearch. This feature was introduced as
experimental in OpenSearch 2.3 and is planned for general availability
in 2.9. Some significant issues and PRs authored by Sachin for this
effort are as follows:

Feature proposal: opensearch-project#1968
Upload segments to remote store post refresh: opensearch-project#3460
Add rest endpoint for remote store restore: opensearch-project#3576
Add RemoteSegmentStoreDirectory to interact with remote segment store: opensearch-project#4020

In total, Sachin has authored 57 PRs going back to May 2022. He also
frequently reviews contributions from others and has reviewed nearly 100
PRs in the same time frame.

Signed-off-by: Andrew Ross <andrross@amazon.com>

.github/CODEOWNERS

@@ -1 +1 @@
-*   @reta @anasalkouz @andrross @reta @Bukhtawar @CEHENKLE @dblock @gbbafna @setiah @kartg @kotwanikunal @mch2 @nknize @owaiskazi19 @Rishikesh1159 @ryanbogan @saratvemulapalli @shwetathareja @dreamer-89 @tlfeng @VachaShah @dbwiddis
+*   @reta @anasalkouz @andrross @reta @Bukhtawar @CEHENKLE @dblock @gbbafna @setiah @kartg @kotwanikunal @mch2 @nknize @owaiskazi19 @Rishikesh1159 @ryanbogan @saratvemulapalli @shwetathareja @dreamer-89 @tlfeng @VachaShah @dbwiddis @sachinpkale

MAINTAINERS.md

@@ -1,39 +1,39 @@
-- [Current Maintainers](#current-maintainers)
-- [Emeritus](#emeritus)
+## Overview
+
+This document contains a list of maintainers in this repo. See [opensearch-project/.github/RESPONSIBILITIES.md](https://github.com/opensearch-project/.github/blob/main/RESPONSIBILITIES.md#maintainer-responsibilities) that explains what the role of maintainer means, what maintainers do in this and other repos, and how they should be doing it. If you're interested in contributing, and becoming a maintainer, see [CONTRIBUTING](CONTRIBUTING.md).
 
 ## Current Maintainers
 
-| Maintainer | GitHub ID | Affiliation |
-| --------------- | --------- | ----------- |
-| Anas Alkouz | [anasalkouz](https://github.com/anasalkouz) | Amazon |
-| Andrew Ross   | [andrross](https://github.com/andrross)| Amazon |
-| Andriy Redko | [reta](https://github.com/reta) | Aiven |
-| Bukhtawar Khan | [Bukhtawar](https://github.com/Bukhtawar) | Amazon |
-| Charlotte Henkle | [CEHENKLE](https://github.com/CEHENKLE) | Amazon |
-| Dan Widdis | [dbwiddis](https://github.com/dbwiddis) | Amazon |
-| Daniel "dB." Doubrovkine | [dblock](https://github.com/dblock) | Amazon |
-| Gaurav Bafna | [gbbafna](https://github.com/gbbafna) | Amazon |
-| Himanshu Setia | [setiah](https://github.com/setiah) | Amazon |
-| Kartik Ganesh | [kartg](https://github.com/kartg) | Amazon |
-| Kunal Kotwani | [kotwanikunal](https://github.com/kotwanikunal) | Amazon |
-| Marc Handalian | [mch2](https://github.com/mch2) | Amazon |
-| Nick Knize | [nknize](https://github.com/nknize) | Amazon |
-| Owais Kazi | [owaiskazi19](https://github.com/owaiskazi19) | Amazon |
-| Rishikesh Pasham | [Rishikesh1159](https://github.com/Rishikesh1159) | Amazon|
-| Ryan Bogan | [ryanbogan](https://github.com/ryanbogan) | Amazon |
-| Sarat Vemulapalli | [saratvemulapalli](https://github.com/saratvemulapalli) | Amazon |
-| Shweta Thareja | [shwetathareja](https://github.com/shwetathareja) | Amazon |
-| Suraj Singh | [dreamer-89](https://github.com/dreamer-89) | Amazon |
-| Tianli Feng | [tlfeng](https://github.com/tlfeng) | Amazon |
-| Vacha Shah | [VachaShah](https://github.com/VachaShah) | Amazon |
+| Maintainer               | GitHub ID                                               | Affiliation |
+|--------------------------| ------------------------------------------------------- | ----------- |
+| Anas Alkouz              | [anasalkouz](https://github.com/anasalkouz)             | Amazon      |
+| Andrew Ross              | [andrross](https://github.com/andrross)                 | Amazon      |
+| Andriy Redko             | [reta](https://github.com/reta)                         | Aiven       |
+| Bukhtawar Khan           | [Bukhtawar](https://github.com/Bukhtawar)               | Amazon      |
+| Charlotte Henkle         | [CEHENKLE](https://github.com/CEHENKLE)                 | Amazon      |
+| Dan Widdis               | [dbwiddis](https://github.com/dbwiddis)                 | Amazon      |
+| Daniel "dB." Doubrovkine | [dblock](https://github.com/dblock)                     | Amazon      |
+| Gaurav Bafna             | [gbbafna](https://github.com/gbbafna)                   | Amazon      |
+| Himanshu Setia           | [setiah](https://github.com/setiah)                     | Amazon      |
+| Kartik Ganesh            | [kartg](https://github.com/kartg)                       | Amazon      |
+| Kunal Kotwani            | [kotwanikunal](https://github.com/kotwanikunal)         | Amazon      |
+| Marc Handalian           | [mch2](https://github.com/mch2)                         | Amazon      |
+| Nick Knize               | [nknize](https://github.com/nknize)                     | Amazon      |
+| Owais Kazi               | [owaiskazi19](https://github.com/owaiskazi19)           | Amazon      |
+| Rishikesh Pasham         | [Rishikesh1159](https://github.com/Rishikesh1159)       | Amazon      |
+| Ryan Bogan               | [ryanbogan](https://github.com/ryanbogan)               | Amazon      |
+| Sachin Kale              | [sachinpkale](https://github.com/sachinpkale)           | Amazon      |
+| Sarat Vemulapalli        | [saratvemulapalli](https://github.com/saratvemulapalli) | Amazon      |
+| Shweta Thareja           | [shwetathareja](https://github.com/shwetathareja)       | Amazon      |
+| Suraj Singh              | [dreamer-89](https://github.com/dreamer-89)             | Amazon      |
+| Tianli Feng              | [tlfeng](https://github.com/tlfeng)                     | Amazon      |
+| Vacha Shah               | [VachaShah](https://github.com/VachaShah)               | Amazon      |
 
 ## Emeritus
 
-| Maintainer | GitHub ID | Affiliation |
-| --------------- | --------- | ----------- |
-| Abbas Hussain | [abbashus](https://github.com/abbashus) | Amazon |
-| Megha Sai Kavikondala | [meghasaik](https://github.com/meghasaik) | Amazon |
-| Rabi Panda | [adnapibar](https://github.com/adnapibar) | Amazon |
-| Xue Zhou | [xuezhou25](https://github.com/xuezhou25) | Amazon |
-
-[This document](https://github.com/opensearch-project/.github/blob/main/MAINTAINERS.md) explains what maintainers do in this repo, and how they should be doing it. If you're interested in contributing, see [CONTRIBUTING](CONTRIBUTING.md).
+| Maintainer              | GitHub ID                                   | Affiliation |
+|-------------------------|---------------------------------------------| ----------- |
+| Abbas Hussain           | [abbashus](https://github.com/abbashus)     | Amazon      |
+| Megha Sai Kavikondala   | [meghasaik](https://github.com/meghasaik)   | Amazon      |
+| Rabi Panda              | [adnapibar](https://github.com/adnapibar)   | Amazon      |
+| Xue Zhou                | [xuezhou25](https://github.com/xuezhou25)   | Amazon      |