(svn r26394) -Fix[FS#5939]: Don't explain "symmetric" cargodist mode when the setting does not allow it.

src/lang/english.txt

@@ -1585,7 +1585,7 @@ STR_CONFIG_SETTING_DISTRIBUTION_MAIL_HELPTEXT                   :"symmetric" mea
 STR_CONFIG_SETTING_DISTRIBUTION_ARMOURED                        :Distribution mode for the ARMOURED cargo class: {STRING2}
 STR_CONFIG_SETTING_DISTRIBUTION_ARMOURED_HELPTEXT               :The ARMOURED cargo class contains valuables in the temperate, diamonds in the subtropical or gold in subarctic climate. NewGRFs may change that. "symmetric" means that roughly the same amount of that cargo will be sent from a station A to a station B as from B to A. "asymmetric" means that arbitrary of that cargo can be sent in either direction. "manual" means that no automatic distribution will take place for that cargo. It is recommended to set this to asymmetric or manual when playing subarctic, as banks won't send any gold back to gold mines. For temperate and subtropical you can also choose symmetric as banks will send valuables back to the origin bank of some load of valuables.
 STR_CONFIG_SETTING_DISTRIBUTION_DEFAULT                         :Distribution mode for other cargo classes: {STRING2}
-STR_CONFIG_SETTING_DISTRIBUTION_DEFAULT_HELPTEXT                :"symmetric" means that roughly the same amount of cargo will be sent from a station A to a station B as from B to A. "asymmetric" means that arbitrary amounts of cargo can be sent in either direction. "manual" means that no automatic distribution will take place for those cargos. You probably want to set this to either "asymmetric" or manual.
+STR_CONFIG_SETTING_DISTRIBUTION_DEFAULT_HELPTEXT                :"asymmetric" means that arbitrary amounts of cargo can be sent in either direction. "manual" means that no automatic distribution will take place for those cargoes.
 STR_CONFIG_SETTING_LINKGRAPH_ACCURACY                           :Distribution accuracy: {STRING2}
 STR_CONFIG_SETTING_LINKGRAPH_ACCURACY_HELPTEXT                  :The higher you set this the more CPU time the calculation of the link graph will take. If it takes too long you may notice lag. If you set it to a low value, however, the distribution will be inaccurate, and you may notice cargo not being sent to the places you expect it to go.
 STR_CONFIG_SETTING_DEMAND_DISTANCE                              :Effect of distance on demands: {STRING2}