docs: add Tinkerbell provider to CAPI book

Author: oscr

docs/book/src/reference/providers.md

@@ -27,7 +27,6 @@ updated info about which API version they are supporting.
 - [Equinix Metal (formerly Packet)](https://github.com/kubernetes-sigs/cluster-api-provider-packet)
 - [GCP](https://github.com/kubernetes-sigs/cluster-api-provider-gcp)
 - [Hetzner](https://github.com/syself/cluster-api-provider-hetzner)
-- [Outscale](https://github.com/outscale-dev/cluster-api-provider-outscale)
 - [IBM Cloud](https://github.com/kubernetes-sigs/cluster-api-provider-ibmcloud)
 - [KubeKey](https://github.com/kubesphere/kubekey)
 - [KubeVirt](https://github.com/kubernetes-sigs/cluster-api-provider-kubevirt)
@@ -38,7 +37,9 @@ updated info about which API version they are supporting.
 - [Nutanix](https://github.com/nutanix-cloud-native/cluster-api-provider-nutanix)
 - [OCI](https://github.com/oracle/cluster-api-provider-oci)
 - [OpenStack](https://github.com/kubernetes-sigs/cluster-api-provider-openstack)
+- [Outscale](https://github.com/outscale-dev/cluster-api-provider-outscale)
 - [Sidero](https://github.com/siderolabs/sidero)
+- [Tinkerbell](https://github.com/tinkerbell/cluster-api-provider-tinkerbell)
 - [vcluster](https://github.com/loft-sh/cluster-api-provider-vcluster)
 - [Virtink](https://github.com/smartxworks/cluster-api-provider-virtink)
 - [VMware Cloud Director](https://github.com/vmware/cluster-api-provider-cloud-director)