Move the old release notes to a separate file

Preparation for reno adoption in a following patch

Change-Id: Ice4f45147ae9699a5be2c60c0ed247b893881d62

doc/source/history.rst

@@ -0,0 +1,28 @@
+Release Notes
+=============
+
+2.2.2
+-----
+
+* improved support for listing a large number of filtered subnets
+* add --endpoint-type and OS_ENDPOINT_TYPE to shell client
+* made the publicURL the default endpoint instead of adminURL
+* add ability to update security group name (requires 2013.2-Havana or later)
+* add flake8 and pbr support for testing and building
+
+2.2.0
+-----
+
+* add security group commands
+* add Lbaas commands
+* allow options put after positional arguments
+* add NVP queue and net gateway commands
+* add commands for agent management extensions
+* add commands for DHCP and L3 agents scheduling
+* support XML request format
+* support pagination options
+
+2.0
+-----
+
+* support Neutron API 2.0

doc/source/index.rst

@@ -56,30 +56,4 @@ Developer Docs
    :maxdepth: 1
 
    devref/index
-
+   history
-
-Release Notes
-=============
-
-2.0
------
-* support Neutron API 2.0
-
-2.2.0
------
-* add security group commands
-* add Lbaas commands
-* allow options put after positional arguments
-* add NVP queue and net gateway commands
-* add commands for agent management extensions
-* add commands for DHCP and L3 agents scheduling
-* support XML request format
-* support pagination options
-
-2.2.2
------
-* improved support for listing a large number of filtered subnets
-* add --endpoint-type and OS_ENDPOINT_TYPE to shell client
-* made the publicURL the default endpoint instead of adminURL
-* add ability to update security group name (requires 2013.2-Havana or later)
-* add flake8 and pbr support for testing and building