+ Update PPTs

README.md

@@ -75,6 +75,7 @@ You can use it to:
     * [FlatMap](docs/cn/flatmap.md)
     * [brpc外功修炼宝典](docs/cn/brpc_intro.pptx)(training material)
     * [A tutorial on building large-scale services](docs/en/tutorial_on_building_services.pptx)(training material)
+    * [brpc internal](docs/en/brpc_internal.pptx)(training material)
   * RPC in depth
     * [New Protocol](docs/en/new_protocol.md)
     * [Atomic instructions](docs/en/atomic_instructions.md)

README_cn.md

@@ -76,6 +76,7 @@
     * [FlatMap](docs/cn/flatmap.md)
     * [brpc外功修炼宝典](docs/cn/brpc_intro.pptx)(培训材料)
     * [搭建大型服务入门](docs/en/tutorial_on_building_services.pptx)(培训材料)
+    * [brpc内功修炼宝典](docs/en/brpc_internal.pptx)(培训材料)
   * 深入RPC
     * [New Protocol](docs/cn/new_protocol.md)
     * [Atomic instructions](docs/cn/atomic_instructions.md)