docs(adapters): adds docs to collateral adapter

Signed-off-by: Bryan Cole <[email protected]>

Author: ColePBryan

tap_core/src/adapters/collateral_adapter.rs

@@ -3,11 +3,49 @@
 
 use ethereum_types::Address;
 
+/// `CollateralAdapter` defines a trait for adapters to handle collateral related operations.
+///
+/// This trait is designed to be implemented by users of this library who want to
+/// customize the management of local accounting for available collateral. The error handling is also
+/// customizable by defining an `AdapterError` type, which must implement both `Error`
+/// and `Debug` from the standard library.
+///
+/// # Usage
+///
+/// The `get_available_collateral` method should be used to retrieve the local accounting
+///  amount of available collateral for a specified gateway. Any errors during this operation
+/// should be captured and returned in the `AdapterError` format.
+///
+/// The `subtract_collateral` method is used to deduct a specified value from the local accounting
+/// of available collateral of a specified gateway. Any errors during this operation should be captured
+/// and returned as an `AdapterError`.
+///
+/// This trait is utilized by [crate::tap_manager], which relies on these
+/// operations for managing collateral.
+///
+/// # Example
+///
+/// For example code see [crate::adapters::collateral_adapter_mock]
+
 pub trait CollateralAdapter {
-    /// User defined error type;
-    type AdapterError: std::error::Error + std::fmt::Debug;
+    /// Defines the user-specified error type.
+    ///
+    /// This error type should implement the `Error` and `Debug` traits from the standard library.
+    /// Errors of this type are returned to the user when an operation fails.
+    type AdapterError: std::error::Error + std::fmt::Debug + Send + Sync + 'static;
 
+    /// Retrieves the local accounting amount of available collateral for a specified gateway.
+    ///
+    /// This method should be implemented to fetch the local accounting amount of available collateral for a
+    /// specified gateway from your system. Any errors that occur during this process should
+    /// be captured and returned as an `AdapterError`.
     fn get_available_collateral(&self, gateway_id: Address) -> Result<u128, Self::AdapterError>;
+
+    /// Deducts a specified value from the local accounting of available collateral for a specified gateway.
+    ///
+    /// This method should be implemented to deduct a specified value from the local accounting of
+    /// available collateral of a specified gateway in your system. Any errors that occur during this
+    /// process should be captured and returned as an `AdapterError`.
     fn subtract_collateral(
         &mut self,
         gateway_id: Address,