docs: add note about freqUI support of dp.current_whitelist

closes #10600

docs/freq-ui.md

@@ -58,7 +58,6 @@ The plot configuration can be accessed via the "Plot Configurator" (Cog icon) bu
 
 ### Settings
 
-
 Several UI related settings can be changed by accessing the settings page.
 
 Things you can change (among others):

docs/strategy-customization.md

@@ -717,6 +717,7 @@ This is where calling `self.dp.current_whitelist()` comes in handy.
 
 ??? Note "Plotting with current_whitelist"
     Current whitelist is not supported for `plot-dataframe`, as this command is usually used by providing an explicit pairlist - and would therefore make the return values of this method misleading.
+    It's also not supported for freqUI visualization in [webserver mode](utils.md#webserver-mode) - as the configuration for webserver mode doesn't require a pairlist to be set.
 
 ### *get_pair_dataframe(pair, timeframe)*