update e-mail list

Author: japaric

README.md

@@ -356,12 +356,14 @@ most of them are members of one of the teams listed above.
 Each team can be privately contacted via the following e-mail addresses:
 
 - cortex-m@teams.rust-embedded.org
+- cortex-r@teams.rust-embedded.org
 - embedded-linux@teams.rust-embedded.org
 - hal@teams.rust-embedded.org
-- msp430@teams.rust-embedded.org
-- riscv@teams.rust-embedded.org
+- infrastructure@teams.rust-embedded.org
 - resources@teams.rust-embedded.org
 - tools@teams.rust-embedded.org
+<!-- - msp430@teams.rust-embedded.org -->
+<!-- - riscv@teams.rust-embedded.org -->
 
 You can usually find the members of the embedded WG on the #rust-embedded channel (server:
 irc.mozilla.org).