fix: added doc block.

crates/btc-relay/src/lib.rs

@@ -1271,14 +1271,34 @@ impl<T: Config> Pallet<T> {
         Ok(())
     }
 
+    /// The target value represents the mining difficulty required to mine a block with the specified hash.
+    ///
+    /// # Parameters
+    ///
+    /// * `block_hash`: A 256-bit block hash.
+    ///
+    /// # Returns
+    ///
+    /// * `Result<u32, DispatchError>`: A `Result` containing the retrieved target value as a `u32` if successful, or a
+    ///   `DispatchError` if an error occurs during the retrieval.
     fn get_target(block_hash: H256Le) -> Result<u32, DispatchError> {
         let block_header = Self::get_block_header_from_hash(block_hash)?;
         // Fixme: Should this be kept as a U256 type and other u32 type can be converted to U256?
         // Currently taking low_u32/as_u32 loses precision
         Ok(block_header.block_header.target.low_u32())
     }
 
-    // Reference: https://github.com/spesmilo/electrum/blob/cee22abcb5544c5a6fa7f8a8108ccda9c32c2e29/electrum/blockchain.py#L582-L588
+    /// Calculates the chainwork of a block header at a given height based on the provided block hash.
+    /// Reference: https://github.com/spesmilo/electrum/blob/cee22abcb5544c5a6fa7f8a8108ccda9c32c2e29/electrum/blockchain.py#L582-L588
+    ///
+    /// # Arguments
+    ///
+    /// * `block_hash`: A 256-bit block hash.
+    ///
+    /// # Returns
+    ///
+    /// * `Result<u32, DispatchError>`: A `Result` containing the calculated chainwork as a `u32` if successful, or a
+    ///   `DispatchError` if an error occurs during target retrieval.
     fn chainwork_of_header_at_height(block_hash: H256Le) -> Result<u32, DispatchError> {
         let target = Self::get_target(block_hash)?;
         let work = (2_u32.saturating_pow(256).saturating_sub(target).saturating_less_one())
@@ -1287,8 +1307,17 @@ impl<T: Config> Pallet<T> {
         Ok(work)
     }
 
-    // Reference: https://github.com/spesmilo/electrum/blob/cee22abcb5544c5a6fa7f8a8108ccda9c32c2e29/electrum/blockchain.py#L589-L614
-    // Calculate the cumulative chainwork of a blockchain.
+    /// The chainwork is a measure of the total computational work done by the chain up to a certain point.
+    /// Reference: https://github.com/spesmilo/electrum/blob/cee22abcb5544c5a6fa7f8a8108ccda9c32c2e29/electrum/blockchain.py#L589-L614
+    ///
+    /// # Parameters
+    ///
+    /// * `chain`: new blockchain element
+    ///
+    /// # Returns
+    ///
+    /// * `Result<u32, DispatchError>`: A `Result` containing the calculated cumulative chainwork as a `u32` if
+    ///   successful, or a `DispatchError` if an error occurs during the calculation.
     fn get_chainwork(chain: BlockChain) -> Result<u32, DispatchError> {
         // Calculate the height of the last retarget point.
         let last_retarget = chain