pw_rpc: Module boilerplate

This change creates the pw_rpc module with all of the standard Pigweed
module boilerplate.

Change-Id: Iac3951a81a0edd286a8b1c7e19c614a7b73c0d07
diff --git a/pw_rpc/docs.rst b/pw_rpc/docs.rst
new file mode 100644
index 0000000..e446c3b
--- /dev/null
+++ b/pw_rpc/docs.rst
@@ -0,0 +1,15 @@
+.. default-domain:: cpp
+
+.. highlight:: sh
+
+.. _chapter-pw-rpc:
+
+------
+pw_rpc
+------
+The ``pw_rpc`` module provides a system for defining and invoking remote
+procedure calls (RPCs) on a device.
+
+.. note::
+
+  Under construction.