fix: Update 8021 docs to include dataSuffix capability

[dgca]

What changed? Why?

Added a new documentation page for the dataSuffix capability in the Base Account reference section. This capability (defined in ERC-8021) allows apps to append arbitrary hex-encoded bytes to transaction calldata for attribution tracking, enabling platforms to identify which app originated a transaction.

Notes to reviewers

How has it been tested?

Local verification with mintlify dev

[cb-heimdall]

✅ Heimdall Review Status

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[youssefea]

Thanks for this contribution ! Would it be possible to make dataSuffix page follow the example of other pages such as flowControl, paymasterService etc?

The only exception there now is dataCallback and that's because it has some additional API examples. I'll be transitioning some of that content soon to match the rest.

[cb-heimdall]

Review Error for youssefea @ 2026-01-12 12:31:46 UTC
User failed mfa authentication, either user does not exist or public email is not set on your github profile. \ see go/mfa-help

[youssefea]

Please add a title here if you can

[youssefea]

Small nit: adding the title to the code snippet

[cb-heimdall]

Review Error for youssefea @ 2026-01-13 14:51:36 UTC
User failed mfa authentication, either user does not exist or public email is not set on your github profile. \ see go/mfa-help