docs: add docs for RTD #1255

Job	Run time
Build	55s
Build	55s
Integration (1.7.*, 5.21/stable, lxd, 5.21, 2.9)	34m 15s
Integration (1.7.*, 5.21/stable, lxd, 5.21, 2.9)	34m 15s
Integration (1.7.*, 5.21/stable, lxd, 5.21, 3)	34m 46s
Integration (1.7.*, 5.21/stable, lxd, 5.21, 3)	34m 46s
Integration (1.7.*, 5.21/stable, microk8s, 1.28-strict, 3.1)	45m 40s
Integration (1.7.*, 5.21/stable, microk8s, 1.28-strict, 3.1)	45m 40s
Integration (1.7.*, 5.21/stable, microk8s, 1.28-strict, 3)	13m 50s
Integration (1.7.*, 5.21/stable, microk8s, 1.28-strict, 3)	13m 50s
Integration (1.8.*, 5.21/stable, lxd, 5.21, 2.9)	30m 33s
Integration (1.8.*, 5.21/stable, lxd, 5.21, 2.9)	30m 33s
Integration (1.8.*, 5.21/stable, lxd, 5.21, 3)	30m 53s
Integration (1.8.*, 5.21/stable, lxd, 5.21, 3)	30m 53s
Integration (1.8.*, 5.21/stable, microk8s, 1.28-strict, 3.1)	45m 39s
Integration (1.8.*, 5.21/stable, microk8s, 1.28-strict, 3.1)	45m 39s
Integration (1.8.*, 5.21/stable, microk8s, 1.28-strict, 3)	13m 36s
Integration (1.8.*, 5.21/stable, microk8s, 1.28-strict, 3)	13m 36s
Integration (1.9.*, 5.21/stable, lxd, 5.21, 2.9)	31m 1s
Integration (1.9.*, 5.21/stable, lxd, 5.21, 2.9)	31m 1s
Integration (1.9.*, 5.21/stable, lxd, 5.21, 3)	31m 4s
Integration (1.9.*, 5.21/stable, lxd, 5.21, 3)	31m 4s
Integration (1.9.*, 5.21/stable, microk8s, 1.28-strict, 3.1)	58s
Integration (1.9.*, 5.21/stable, microk8s, 1.28-strict, 3.1)	58s
Integration (1.9.*, 5.21/stable, microk8s, 1.28-strict, 3)	53s
Integration (1.9.*, 5.21/stable, microk8s, 1.28-strict, 3)	13m 32s
	10h 40m 45s

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