added pydoc comments to _prepare method of AmentCargoBuildTask method

Author: GueLaKais

colcon_ros_cargo/task/ament_cargo/build.py

@@ -62,6 +62,17 @@ def add_arguments(self, *, parser):  # noqa: D102
             '.cargo/config.toml for subsequent builds with cargo.')
 
     def _prepare(self, env, additional_hooks):
+        """
+        Prepare the build environment.
+
+        This method resolves the package paths for dependencies, writes the
+        resolved paths to a .cargo/config.toml file, and creates an environment
+        hook for the AMENT_PREFIX_PATH.
+
+        Args:
+            env: The environment to prepare.
+            additional_hooks: Additional hooks to be executed.
+        """
         args = self.context.args
 
         global package_paths