SessionManager: fix typo maxUserSession(s)
SessionManager: fix typo maxUserSession(s)

Server fails to start with:

Application 16:16:49.306 16187
	[Error] Not found: missing number setter maxUserSession (:0)

Fixes: 4309500be7f7 ("SessionManager: introduce sessionExpireTime and maxUserSessions")
Signed-off-by: Jan Viktorin <3eab6ac54c005c4408f608556a6663b7f2abede7@fit.vutbr.cz>

BeeeOn/server,BeeeOn/server,BeeeOn/server,BeeeOn/server