feat(Module): add ReactionManager to exports (#4372)

add ReactionManager to the manager exports in src/index.js

closes #4363

Author: camc

src/index.js

@@ -40,6 +40,7 @@ module.exports = {
   GuildMemberManager: require('./managers/GuildMemberManager'),
   GuildMemberRoleManager: require('./managers/GuildMemberRoleManager'),
   GuildManager: require('./managers/GuildManager'),
+  ReactionManager: require('./managers/ReactionManager'),
   ReactionUserManager: require('./managers/ReactionUserManager'),
   MessageManager: require('./managers/MessageManager'),
   PresenceManager: require('./managers/PresenceManager'),