docs: Simplify email testing notes section.
docs: Simplify email testing notes section.

No good reason for one note to be bold compared to
other notes.

zulip/zulip,punchagan/zulip,rht/zulip,kou/zulip,zulip/zulip,eeshangarg/zulip,hackerkid/zulip,andersk/zulip,andersk/zulip,zulip/zulip,rht/zulip,showell/zulip,showell/zulip,kou/zulip,showell/zulip,showell/zulip,punchagan/zulip,kou/zulip,punchagan/zulip,rht/zulip,rht/zulip,andersk/zulip,eeshangarg/zulip,rht/zulip,andersk/zulip,kou/zulip,hackerkid/zulip,zulip/zulip,zulip/zulip,eeshangarg/zulip,kou/zulip,eeshangarg/zulip,kou/zulip,rht/zulip,andersk/zulip,hackerkid/zulip,rht/zulip,punchagan/zulip,andersk/zulip,punchagan/zulip,andersk/zulip,zulip/zulip,hackerkid/zulip,eeshangarg/zulip,showell/zulip,hackerkid/zulip,eeshangarg/zulip,showell/zulip,eeshangarg/zulip,punchagan/zulip,hackerkid/zulip,zulip/zulip,kou/zulip,punchagan/zulip,hackerkid/zulip,showell/zulip