docs: add Cohort 6 information of the delegation program (#2326)

* add Cohort 6 information

* Apply suggestions from code review

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

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

Author: 3 people

community/foundation-delegation-program.md

@@ -168,5 +168,6 @@ their respective delegations.
 - [Cohort 3](https://docs.google.com/spreadsheets/d/1Fxu9uYJ4wxfHChEiSg5bmXAMU8IZSq7J3GYDCFgk1HA/edit?gid=1432570846#gid=1432570846): 15 Validator Seats (Applications open October 1, 2024)
 - [Cohort 4](https://docs.google.com/spreadsheets/d/1Fxu9uYJ4wxfHChEiSg5bmXAMU8IZSq7J3GYDCFgk1HA/edit?gid=1814073511#gid=1814073511): 20 Validator Seats (Applications open February 1, 2025)
 - [Cohort 5](https://docs.google.com/spreadsheets/d/1Fxu9uYJ4wxfHChEiSg5bmXAMU8IZSq7J3GYDCFgk1HA/edit?gid=1471991269#gid=1471991269): 15 Validator Seats (Applications open June 1, 2025)
+- [Cohort 6](https://docs.google.com/spreadsheets/d/1Fxu9uYJ4wxfHChEiSg5bmXAMU8IZSq7J3GYDCFgk1HA/edit?gid=1010270944): 15 Validator Seats (Applications open October 1, 2025)
 
 IMPORTANT: Each validator selected for the program has to maintain a fully archival (non pruned) bridge node for both Mainnet Beta and Mocha.