fa365021bbb4c0865e6655100c1cbf85e2b3c7fa doc: Remove outdated net comment (MarcoFalke)
Pull request description:
`mapAddresses` and the corresponding "critsect" has been removed in 5fee401fe14aa6459428a26a82f764db70a6a0b9 more than 6 years ago. Now is probably a good time to remove this confusing comment.
Tree-SHA512: 498a403d5703da395c18a7ebb776aa6e693e59fe43a839fefd261e0a5af58621763813979d4cfbd8d1728ce73b325b82002e393cde79bdbff33e0fbf68ab6747
Backport of Core PR13824
https://github.com/bitcoin/bitcoin/pull/13824/