docs Add NTT DATA to partners list (a2aproject#1200)

Update partners with NTT DATA

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Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com>

Author: Yotaro111

docs/partners.md

@@ -103,6 +103,7 @@ collaborate effectively with each other and with users.
 - [New Relic](https://newrelic.com)
 - [Nisum](http://www.nisum.com)
 - [Noorle Inc](http://www.noorle.com)
+- [NTT DATA](https://www.nttdata.com)
 - [Optimizely Inc](https://www.optimizely.com/)
 - [Oracle / NetSuite](https://www.oracle.com/netsuite)
 - [Palo Alto Networks](https://www.paloaltonetworks.com/)