Update contributor doc

1. Remove some invalid links
2. Remove `paste` related doc
3. Fix some nits.

Change-Id: Iefdc12dd3b93ff7b2d6df635bc849a0c9b42f171

doc/source/contributor/http-api.rst

@@ -19,14 +19,13 @@ Specifications
 ==============
 
 As of the Queens release, Keystone solely implements the `Identity API v3`_.
-Support for `Identity API v2.0`_ has been removed in Queens in favor of
+Support for Identity API v2.0 has been removed in Queens in favor of
 the `Identity API v3`_.
 
 Identity API v3 is a superset of all the functionality available in the
 Identity API v2.0 and several of its extensions, and provides a much more
 consistent developer experience.
 
-.. _`Identity API v2.0`: https://developer.openstack.org/api-ref/identity/v2/
 .. _`Identity API v3`: https://developer.openstack.org/api-ref/identity/v3/
 
 History
@@ -53,44 +52,10 @@ How do I migrate from v2.0 to v3?
 I am a deployer
 ---------------
 
-You'll need to ensure the v3 API is included in your Paste pipeline, usually
-``etc/keystone-paste.ini``. Our `latest sample configuration`_ includes the v3
-application pipeline.
-
-First define a v3 application, which refers to the v3 application factory
-method:
-
-.. code-block:: ini
-
-    [app:service_v3]
-    use = egg:keystone#service_v3
-
-Then define a v3 pipeline, which terminates with the v3 application you defined
-above:
-
-.. code-block:: ini
-
-    [pipeline:api_v3]
-    pipeline = ... service_v3
-
-Replace "..." with whatever middleware you'd like to run in front of the API
-service. Our `latest sample configuration`_ documents our tested
-recommendations, but your requirements may vary.
-
-Finally, include the v3 pipeline in at least one ``composite`` application (but
-usually both ``[composite:main]`` and ``[composite:admin]``), for example:
-
-.. code-block:: ini
-
-    [composite:main]
-    use = egg:Paste#urlmap
-    /v3 = api_v3
-    ...
-
-Once your pipeline is configured to expose v3, you need to ensure that you've
-configured your service catalog in Keystone correctly. The simplest, and most
-ideal, configuration would expose one identity with unversioned endpoints (note
-the lack of ``/v2.0/`` or ``/v3/`` in these URLs):
+You need to ensure that you've configured your service catalog in Keystone
+correctly. The simplest, and most ideal, configuration would expose one
+identity with unversioned endpoints (note the lack of ``/v2.0/`` or ``/v3/`` in
+these URLs):
 
 - Service (type: ``identity``)
 
@@ -125,7 +90,6 @@ Keystone clients can use to automatically detect available API versions.
 With unversioned ``identity`` endpoints in the service catalog, you should be
 able to `authenticate with keystoneclient`_ successfully.
 
-.. _`latest sample configuration`: https://git.openstack.org/cgit/openstack/keystone/tree/etc/keystone-paste.ini
 .. _`authenticate with keystoneclient`: https://docs.openstack.org/python-keystoneclient/latest/using-api-v3.html#authenticating-using-sessions
 
 I have a Python client

doc/source/contributor/services.rst

@@ -91,8 +91,7 @@ their own namespace. For example, unlike in v2.0, usernames are no longer
 unique across the deployment. You can have two users with the same name, but
 they must be in different domains. However, user IDs are assigned to users by
 keystone and are expected to be unique across the deployment. All of this logic
-applies to both projects and user groups as well. Note that roles are *not*
-namespaced by domains.
+applies to projects, user groups and roles.
 
 One of the great things about domains is that you can have one domain backed by
 SQL (for service users) and another backed by LDAP (the cloud is deployed into

doc/source/contributor/set-up-keystone.rst

@@ -89,11 +89,10 @@ Deploying configuration files
 =============================
 
 You should be able to run keystone after installing via pip. Additional
-configuration files are required, however. The following files are required in
-order to run keystone:
+configuration files are required. The following file is required in order to
+run keystone:
 
 * ``keystone.conf``
-* ``keystone-paste.ini``
 
 Configuring Keystone with a sample file
 ---------------------------------------