docs: improve Edge connectivity docs #2521

Job	Run time
Build source R package	5m 23s
Coverage	5m 36s
Sanitizer	24m 16s
Check windows-latest (release)	16m 27s
Check macOS-latest (release)	10m 49s
Check ubuntu-20.04 (release)	5m 42s
Check ubuntu-20.04 (devel)	6m 28s
Check ubuntu-20.04 (oldrel-1)	6m 13s
Check ubuntu-20.04 (oldrel-2)	5m 59s
Check ubuntu-20.04 (oldrel-3)	6m 22s
Check ubuntu-20.04 (oldrel-4)	5m 52s
	1h 39m 7s

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