Break up the 'someos' docs classification based on a more user-focused scheme, including creation of a separate 'Concurrent Execution' section
diff --git a/Doc/library/index.rst b/Doc/library/index.rst
index dc35b09..ba20361 100644
--- a/Doc/library/index.rst
+++ b/Doc/library/index.rst
@@ -57,7 +57,7 @@
    fileformats.rst
    crypto.rst
    allos.rst
-   someos.rst
+   concurrency.rst
    ipc.rst
    netdata.rst
    markup.rst