Add load_object to op codes documentation.

doc/dvm.asciidoc

@@ -152,9 +152,27 @@ The source register must contain a `DvmValue::Object` at runtime.
 
 === Load Boolean
 
+=== Load Object
+
+Loads the target register with the `DvmValue::Object` stored at the offset from the base of the object stored in the
+source register.
+
+[source]
+----
+load_object(
+  target_register: u8,
+  source_register: u8,
+  offset: usize
+)
+----
+
+The source register must contain a `DvmValue::Object` at runtime, and the data at the offset from that object's base
+must be a valid `Rc<DvmObject>`.
+
 === Store
 
-Stores the value contained in the source register to the offset from the base of the object contained in the target register.
+Stores the value contained in the source register to the offset from the base of the object contained in the target
+register.
 
 [source]
 ----
@@ -180,7 +198,8 @@ alloc(
 )
 ----
 
-The `implementation_name` is the bytes array of a UTF-8-encoded string, and `implementation_name_length` is the length of that array.
+The `implementation_name` is the bytes array of a UTF-8-encoded string, and `implementation_name_length` is the length
+of that array.
 
 === Deallocate