doc: Introduce documentation for osmo-trx-ipc and its IPC interface

Related: SYS#6861
Change-Id: Id6863731f9398720030b16efaaf559e05f2444ed
diff --git a/doc/manuals/chapters/code-architecture.adoc b/doc/manuals/chapters/code-architecture.adoc
index 1cb2542..5311dbe 100644
--- a/doc/manuals/chapters/code-architecture.adoc
+++ b/doc/manuals/chapters/code-architecture.adoc
@@ -17,6 +17,7 @@
 7[label = "{UHDDevice|...}"]
 8[label = "{LMSDevice|...}"]
 9[label = "{USRPDevice|...}"]
+10[label = "{IPCDevice|...}"]
 
 2->3[arrowtail=odiamond]
 3->4[constraint=false]
@@ -25,6 +26,7 @@
 6->7
 6->8
 6->9
+6->10
 }
 ----