docs: Updating setDomainSuffixMatch() for Android P

Small update to reflect P-related change (that common-name verification
is no longer supported), per
https://android-dot-devsite.googleplex.com/about/versions/p/android-9.0-changes#certificate-common-name

Also added some missing paragraph breaks while I was doing it.

Doc is staged to:

http://go/dac-stage/reference/android/net/wifi/WifiEnterpriseConfig#setDomainSuffixMatch(java.lang.String)

Exempt-From-Owner-Approval: Docs-only change
Bug: 110483059
Test: make ds-docs
Change-Id: I50b6eb70bf16c17dd0ae4e54711c5bb599c47c1a