Docs: Add missing RST docs

Adds dcos.rst files for all modules lacking documentation.

Change-Id: Ief5594831d31fcb876381a4a3886382fab7d595e
diff --git a/pw_sys_io_stdio/docs.rst b/pw_sys_io_stdio/docs.rst
index 553efbf..d4c1954 100644
--- a/pw_sys_io_stdio/docs.rst
+++ b/pw_sys_io_stdio/docs.rst
@@ -36,4 +36,4 @@
 
 Dependencies
 ============
-  * pw_sys_io facade
+  * ``pw_sys_io`` facade