Update Contracts FAQ (#7930)

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## PR-Codex overview
This PR adds new information to the `page.mdx` file regarding deployment costs and auditing of thirdweb contracts.

### Detailed summary
- Added a new `Details` section on deployment costs for thirdweb contracts, outlining:
  - Mint fees and primary sales fees for specific contract types.
  - A 2% convenience fee and a 0.5% protocol fee on primary sales.
  - Clarified that fees apply only to prebuilt contracts via the dashboard.
- Included information about thirdweb contracts being audited by third-party firms.

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<!-- This is an auto-generated comment: release notes by coderabbit.ai -->
## Summary by CodeRabbit

* **Documentation**
  * Added an FAQ explaining costs for deploying prebuilt contracts via the dashboard.
  * Clarifies a 2% dashboard deployment fee plus a 0.5% protocol fee (total 2.5%) taken from primary sales.
  * Includes an example payout and lists affected contract categories.
  * Notes that custom or externally deployed contracts are exempt.
  * Specifies fees are deducted in the sale’s currency and placed after the existing FAQ on using thirdweb with existing contracts.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->

Author: saminacodes

apps/portal/src/app/contracts/faqs/page.mdx

@@ -21,6 +21,23 @@ For any already deployed contracts, you can use the thirdweb dashboard to import
 
 </Details>
 
+<Details summary="Does it cost money to deploy contracts on thirdweb?">
+Only thirdweb pre-built contracts have mint fees or fees taken on primary sales for the following contracts which have a primary recipient field:
+
+- Drop Contracts: DropERC20, DropERC721, DropERC1155, OpenEdition
+- Token Contracts: TokenERC20, TokenERC721, TokenERC1155
+- Specialized Contracts: , LoyaltyCard, BurnToClaim, MarketplaceV3
+
+There is a 2% convenience fee for deploying from the dashboard and a 0.5% protocol fee that is integrated into the contract. 
+
+The 2.5% fee will be automatically deducted from primary sales executed through these contracts. For example, an asset listed at 0.1 ETH will distribute 0.0975 ETH to the seller and 0.0025 ETH to the platform.
+
+The fee applies only to prebuilt contracts deployed via the thirdweb dashboard. Custom contracts or externally deployed contracts are not subject to fees. 
+
+The fee is charged from the primary sale, including a claim or mint action when there is a price on the NFT (non-zero). The fee is paid in the same currency as the claiming or minting price.
+
+</Details>
+
 <Details summary="Are thirdweb contracts audited?">
 Yes, thirdweb pre-built contracts are audited by third-party security firms. You can see the attached
 audit reports for each contract linked on the contract page on Explore.