changelog and notes

Signed-off-by: Danno Ferrin <danno.ferrin@gmail.com>

CHANGELOG.md

@@ -1,5 +1,13 @@
 # Changelog
 
+## 1.4 RC 
+
+### Additions and Improvements 
+
+- New`trace_replayBlockTransactions` JSON-RPC API
+
+This can be enabled via the `--rpc-http-api TRACE` CLI flag.  There are some philosophical differences between Besu and other implementations that are outlined in the `[trace_rpc_apis.md](./docs/trace_rpc_apis.md)` documentation.
+
 ## 1.4 Beta 3 
 
 ### Additions and Improvements 

docs/trace_rpc_apis.md

@@ -0,0 +1,37 @@
+# Trace RPC API nodes
+
+This document outlines major differences for `trace_replayBlockTransactions` 
+compared to other implementations.
+
+## `stateDiff` 
+
+No major differences have been observed in the `stateDiff` field.
+
+## `trace`
+
+Besu will report `gasUsed` after applying the effects of gas refunds.  Future
+implementations of Besu may track gas refunds separately.
+
+## `vmTrace`
+
+### Returned Memory from Calls
+
+In the `vmTrace` `ope.ex.mem` fields Besu will only report actual data returned
+fron a `RETURN` opcode.  Other implementations return the contents of the 
+reserved output space for the call operations.  Two major differences will be 
+noted:
+
+1. Besu will report null when a call operation ends because of a `STOP`, `HALT`,
+   `REVERT`, running out of instructions, or any exceptional halts.
+2. When a `RETURN` operation returns data of a different length than the space
+   reserved by the call only the data passed to the `RETURN` operation will be 
+   reported.  Other implementations will include pre-existing memory data or 
+   trim the returned data.
+
+### Precompiled contracts calls
+
+Besu reports only the actual cost of the precompiled contract call in the 
+`"cost"` field. 
+
+
+