docs: Clarify usage of D-Bus and GLib in Install chapter #309

Job	Run time
Build Netatalk testsuite container	58s
Build Netatalk container	49s
Netatalk container dry run	4s
AFP login test - AFP 2.1	6s
AFP spec test (Readonly) - AFP 3.4	5s
AFP spec test (Readonly) - AFP 2.1	8s
AFP login test - AFP 3.4	8s
AFP spec test - AFP 2.1	1m 1s
AFP spec test - AFP 3.0	1m 9s
AFP spec test - AFP 2.2	57s
AFP spec test - AFP 3.1	1m 6s
AFP spec test - AFP 3.2	1m 7s
AFP spec test - AFP 3.3	1m 7s
AFP spec test - AFP 3.4	1m 9s
	9m 54s

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