Add lang-team@ as an alias

Multiple times, people have gotten confused that `lang@` reaches us but
`lang-team@` does not. (This includes people *on* the team.) Add it as
an alias.

Author: joshtriplett

teams/lang.toml

@@ -40,6 +40,9 @@ address = "lang-private@rust-lang.org"
 [[lists]]
 address = "lang@rust-lang.org"
 
+[[lists]]
+address = "lang-team@rust-lang.org"
+
 [[lists]]
 address = "language-design-team@rust-lang.org"