incusd: Fix comments on exported functions #417

Job	Run time
Documentation	6m 18s
Code	6m 46s
Client (1.21.x, ubuntu-latest)	22s
System (1.21.x, cluster, dir)	11m 16s
Client (1.21.x, macos-latest)	1m 14s
System (1.21.x, cluster, btrfs)	12m 1s
Client (1.21.x, windows-latest)	2m 23s
System (1.21.x, cluster, lvm)	13m 18s
System (1.21.x, cluster, zfs)	14m 23s
System (1.21.x, cluster, ceph)	17m 3s
System (1.21.x, cluster, random)	12m 22s
System (1.21.x, standalone, dir)	21m 41s
System (1.21.x, standalone, btrfs)	20m 39s
System (1.21.x, standalone, lvm)	39m 42s
System (1.21.x, standalone, zfs)	41m 56s
System (1.21.x, standalone, ceph)	1h 13m 12s
System (1.21.x, standalone, random)	35m 9s
System (stable, cluster, dir)	10m 42s
System (stable, standalone, dir)	20m 42s
System (tip, cluster, dir)	11m 21s
System (tip, standalone, dir)	23m 12s
	6h 35m 42s

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