Correct 'seessions' (sessions) (#220)

server/env.py

@@ -108,7 +108,7 @@ class Env(lib_util.LoggedClass):
         # We give the DB 250 files; allow ElectrumX 100 for itself
         value = max(0, min(env_value, nofile_limit - 350))
         if value < env_value:
-            self.log_warning('lowered maximum seessions from {:,d} to {:,d} '
+            self.log_warning('lowered maximum sessions from {:,d} to {:,d} '
                              'because your open file limit is {:,d}'
                              .format(env_value, value, nofile_limit))
         return value