docs: add the definition of the square size to methods (#310)

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## Overview

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To avoid needing to explain what the Celestia block size is, this PR
adds that definition to the methods docs.


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

- **Documentation**
- Added clarifying comments to functions in the verification process,
explaining that the square size represents the number of rows of the
original square.

<!-- end of auto-generated comment: release notes by coderabbit.ai -->

src/lib/verifier/DAVerifier.sol

@@ -265,6 +265,7 @@ library DAVerifier {
     }
 
     /// @notice computes the Celestia block square size from a row/column root to data root binary merkle proof.
+    /// The square size is the number of rows of the original square.
     /// Note: the provided proof is not authenticated to the Blobstream smart contract. It is the user's responsibility
     /// to verify that the proof is valid and was successfully committed to using
     //  the `DAVerifier.verifyRowRootToDataRootTupleRoot()` method
@@ -286,6 +287,7 @@ library DAVerifier {
     }
 
     /// @notice computes the Celestia block square size from a shares to row/column root proof.
+    /// The square size is the number of rows of the original square.
     /// Note: the provided proof is not authenticated to the Blobstream smart contract. It is the user's responsibility
     /// to verify that the proof is valid and that the shares were successfully committed to using
     /// the `DAVerifier.verifySharesToDataRootTupleRoot()` method.