Update README.md

Older Ansible versions are now EOL, while 2.12 is still receiving security
updates until May 2023 at least. Also, the devel and nightly setups haven't
used centos7 for a while now.

README.md

@@ -26,7 +26,7 @@ Forklift provides tools to create Foreman/Katello environments for development,
 ### Requirements
 
 * Vagrant - 2.2+ - Both the VirtualBox and Libvirt providers are tested
-* Ansible - 2.9+
+* Ansible - 2.12+
 * [Vagrant Libvirt provider plugin](https://github.com/vagrant-libvirt/vagrant-libvirt) (if using Libvirt)
 * Virtualization enabled in BIOS
 
@@ -107,7 +107,7 @@ Sometimes you want to spin up the same box type (e.g. centos7-katello-devel) fro
 
 ```
 my-nightly-koji:
-  box: centos7
+  box: centos8
   ansible:
     playbook: playbooks/katello.yml
     variables:
@@ -154,7 +154,7 @@ Example with custom networking, static IP on custom libvirt network:
 
 ```
 static:
-  box: centos7
+  box: centos8
   hostname: mystatic.box.com
   networks:
     - type: 'private_network'
@@ -168,7 +168,7 @@ Example with custom libvirt management network:
 
 ```
 static:
-  box: centos7
+  box: centos8
   hostname: mystatic.box.com
   libvirt_options:
     management_network_address: 172.23.99.0/24
@@ -180,8 +180,8 @@ Do not forget to set openstack API credentials.
 To use openstack provider as default look [here](https://www.vagrantup.com/docs/providers/default.html).
 
 ```
-openstack-centos7:
-  image_name: 'Centos7'
+openstack-centos8:
+  image_name: 'Centos8'
   username: 'centos'  #root by default
   hostname: 'john-doe'
   openstack_flavor: 'm1.medium'
@@ -195,7 +195,7 @@ Example with sshfs mounting folder from guest to host:
 
 ```
 with-sshfs:
-  box: centos7
+  box: centos8
   sshfs:
     host_path: '/some/host/path'
     guest_path: '/some/guest/path'
@@ -208,7 +208,7 @@ Additonal options may be specified with using `options`.
 
 ```
 with-sshfs-options:
-  box: centos7
+  box: centos8
   sshfs:
     host_path: '/some/host/path'
     guest_path: '/some/guest/path'
@@ -219,7 +219,7 @@ Example with an additional disk (libvirt volume) presented as /dev/vdb in the vm
 
 ```
 static:
-  box: centos7
+  box: centos8
   hostname: mystatic.box.com
   add_disks:
     - size: 100GiB
@@ -235,7 +235,7 @@ Then create your box:
 
 ```
 with-nfs:
-  box: centos7
+  box: centos8
   nfs:
     host_path: '/some/host/path'
     guest_path: '/some/guest/path'
@@ -276,7 +276,7 @@ Ansible roles may also be installed directly using the [`ansible-galaxy` command
 
 ```
 ansible:
-  box: centos7-katello-nightly
+  box: centos8-katello-nightly
   ansible:
     playbook:
       - 'user_playbooks/vim.yml'