Revert "Consolidate admin guide and configuration guide"

This reverts commit a869abf951.

Actually, we need to have both admin guide and configuration
guide because openstack manual will link to these two guides
respectively.

Change-Id: I1dc4ae9b0258afdc14efdce5664ffb0c7984124d

doc/source/admin/README.rst

@@ -0,0 +1,7 @@
+===============================================
+Zun Administration Documentation (source/admin)
+===============================================
+
+
+This directory is intended to hold any documentation that is related
+to how to run or operate Zun.

doc/source/admin/index.rst

@@ -0,0 +1,15 @@
+Administrator's Guide
+=====================
+
+Installation & Operations
+-------------------------
+
+If you are a system administrator running Zun, this section contains
+information that should help you understand how to deploy, operate, and upgrade
+the services.
+
+.. toctree::
+  :maxdepth: 1
+
+  osprofiler
+  clear-containers

doc/source/configuration/index.rst

@@ -6,5 +6,3 @@ Sample Configuration File
 
     sample-config
     policy
-    osprofiler
-    clear-containers

doc/source/contributor/documentation.rst

@@ -92,6 +92,7 @@ as is documented in the ``README`` in each directory:
 .. toctree::
    :maxdepth: 1
 
+   ../admin/README
    ../cli/README
    ../configuration/README
    ../contributor/README

doc/source/index.rst

@@ -104,6 +104,7 @@ Reference Material
    :maxdepth: 2
 
    cli/index
+   admin/index
    configuration/index
    user/filter-scheduler
    reference/api-microversion-history