Prepare release metadata for openstack.cloud 2.6.0

Bump galaxy.yml to 2.6.0.
Add a 2.6.0 entry in changelogs/changelog.yaml,
regenerate CHANGELOG.rst with antsibull-changelog.

Tests-Run: tox -e pep8

Change-Id: I03a4a424d1f47a9fdaa70efae9b8c9a3fa60b072
Signed-off-by: Grzegorz Koper <grzegorzk@stackhpc.com>

plugins/modules/baremetal_port_group.py

@@ -54,6 +54,7 @@ options:
       choices: ['present', 'absent']
       default: present
       type: str
+version_added: 2.6.0
 extends_documentation_fragment:
 - openstack.cloud.openstack
 '''

plugins/modules/compute_service.py

@@ -32,6 +32,7 @@ options:
     description:
       - Reason for disabling the service. Should be used with state `disabled`.
     type: str
+version_added: 2.6.0
 extends_documentation_fragment:
   - openstack.cloud.openstack
 '''

plugins/modules/network_segment.py

@@ -48,6 +48,7 @@ options:
      choices: ['present', 'absent']
      default: present
      type: str
+version_added: 2.6.0
 extends_documentation_fragment:
 - openstack.cloud.openstack
 '''

plugins/modules/volume_image_metadata.py

@@ -27,6 +27,7 @@ options:
     type: dict
 author:
   - Simon Dodsley (@simondodsley)
+version_added: 2.6.0
 """
 
 EXAMPLES = r"""

plugins/modules/volume_retype.py

@@ -58,6 +58,7 @@ options:
       - Ignored when I(wait=false).
     type: int
     default: 600
+version_added: 2.6.0
 extends_documentation_fragment:
   - openstack.cloud.openstack
 '''